Slartibartfast

That is weird. Does the hub turn freely when it's unlocked? Maybe it's dry, or has some swarf in it from manufacturing?

The knock sensor code doesn't mean that the engine is knocking. If the computer hears something it doesn't like, it pulls ignition timing until the noise goes away, but it doesn't tell you about it. The knock sensor code means the knock sensor isn't working. The manual says to check the sensor (should be 500-620k ohms), check the harness, and loosen and retighten a couple of grounds on the engine. Diag starts on EC-320 of the '02 manual. The catch is that the knock sensor is under the intake manifold. Unless there's a VQ-specific shortcut that I'm not aware of, or you have an exceptionally cooperative pet rat, you'll have to remove the manifold to access the sensor. I had a knock sensor code on my '93 a while back. Turned out the sensor was bad. Unless you hear pinging, I would ignore it until you're back home. The knock sensor is there for emergencies, and not used in normal operation. (I have wondered if the computer might pull timing out of caution if it knows it's got a bad knock sensor, but I have found nothing in the manual to support this.)

With the shudder and the code, yeah, trans shop is probably the way to go if you don't want to chase it yourself. I would do whatever electrical checks the service manual shows for that code on the off chance it's something simple. My mom's Lexus GX470 did the same rumble strip thing when its torque converter clutch started acting up. My dad found a recommendation for some kind of shudder fix goo on a Lexus forum, and to our surprise (and to the surprise of the mechanic who put it in), the goo solved the problem. No idea if that's just a Lexus thing, or if it's worth trying in your case. I don't think a manual hub could cause that rumble if it wanted to. If you want to rule it out, lock the hubs and see if the noise goes away. I had an auto hub make noise once, but it was not a rumble. It sounded like a manual gearbox having its teeth kicked in. Scared the hell out of me.

I used this writeup and the service manual (for torque specs) when I did mine.

Try NissanPartsDeal, Amayama, and Partsouq. Otherwise you're stuck with with aftermarket. I got OE head gaskets from Amayama, shipped from the UAE, somehow cheaper than NPD had them in (I assume?) the US, so check them against each other. But sometimes Amayama turns out not to have what they think they do. I tried ordering a dipstick tube from them, only to get an email the next day that they didn't actually have it. I think they take the order and then see if they can track stuff down from their suppliers. I haven't ordered from Amayama or Partsouq since the tariffs got weird, not sure how they're dealing with that. My dad tried ordering parts from the UK recently and was told they had no idea what the charge would be by the time the stuff got here, and they just didn't want to deal with it, so they weren't even accepting US orders. I got the OE tstat and water pump ("pump ass wat" in Nissan parts speak) via NPD, NSK idler and Bando belt off Rockauto because I couldn't find OE. Can't speak to the quality of either, haven't even installed them, given the engine they were going on turned out to be a doorstop. Years back I put a Gates belt and pump on my VG30, and they're still holding up 30k later, but I've heard some complaints about Gates since.

The transfer case won't come out of 4x if it's under load. Moving the lever doesn't pull it out of 4x, it just allows a spring to push it back out when it can. If it's loaded, either by torque or because you're still on it, it won't disengage, same as you can't get a manual transmission out of gear without using the clutch or letting off the throttle. If it's real balky, change the fluid in the transfer case. My '95 kept getting stuck in 4x until I changed the fluid. That cleared it right up.

Get it as clean as you can, run it for a bit, and see what gets oily again first. Might help narrow it down.

Those shouldn't need hammering. Something ain't right. Check that the numbers on the bearings match the numbers on the box, and check that it's the right part number for the truck. I would also check that you've got the outer races driven into the hub all the way.

I can kinda relate. The PO of mine tinted both front door windows way too dark, significantly darker than the rear windows are tinted from factory. I don't know how people drive like that. I don't normally get claustrophobic, but I felt a whole lot better in there after I peeled that crap off. I've heard good things about the ceramic tint. I'd like to try one of the lighter shades on the side windows. I'm not sure how well it would stick to the sunroof, though. There's some kind of painted crosshatch on the underside that I suspect might be just thick enough to stop it laying down properly. But I've never applied tint, so I don't know. It might be a lot less fussy than I'm assuming it is.

If it's possible this started recently, I'd check for anything that might've loosened up. A friend of mine had the camber adjusters on his Blazer loosen up and slip while he was driving. I don't remember whether it pulled, but I'd imagine it did, given how off the camber was. At the tire real quick, too. You can confirm whether it's toed out with a tape measure. Don't trust the tread blocks to be lined up, I did that once and chased my tail for hours because the treads weren't quite straight. I use angle iron up against the sidewalls, propped up on jackstands (to get them away from the bulge at the bottom of the tire), and measure across. You can measure front and back, but there's always something in the way in the back, so I measure in front, and then the diameter of the tire in front of that. An alignment shop should be able to figure it out pretty quick, if you have a competent one in your area.

The outer seal on mine removed itself! Made a hell of a racket when it came loose at highway speed. I was kind of alarmed at first, until I looked out the window at the truck's shadow and saw the seal flapping around up there like the flailing inflatable tube man things outside a used car dealer. And yeah, glass on a roof is sorta dumb. I like that I can prop mine open when it's hot out, better than leaving windows down, but otherwise it's a liability. And I'm not sure it isn't letting in more heat through the glass than it's venting. I'd be interested to see what you come up with if you delete yours.

Look for a manual car wash, the kind that eats quarters and gives you time with the spray wand. Don't shoot it directly at electrical connectors or fluid caps if you can avoid it, otherwise give 'er hell. I'd spray it down before you get in there. It's much nicer working on something that isn't an oily mess.

I'd hazard a guess that the vehicle speed data point is the average of the four sensors, so it's feeding the speedo (and likely the engine and transmission computers as well) a single data point instead of four. Wouldn't explain the discrepancy between that data point and the speedo, though. That's bizarre. Maybe it's checking that average wheel speed against how fast it thinks it should be going, given the engine RPM and what gear the trans is in, getting confused because the ratios aren't what it expects, and attempting some kind of correction? I've heard of speedo calibration boxes that apply a conversion factor to the speed sensor signal. Seems like it should work, provided the speedo's getting a pulse signal, not reading the data point via canbus or something. Good luck with the inspection! Sucks the cat is still giving you issues, but at least the cooling system is finally working right.

I'll bet the fuel hose is the problem. There are different kinds of rubber used depending on what kind of fluid they're up against. I've heard of (and seen!) rubber meant for cooling systems swell and get squishy when exposed to oil. Looks like fuel line and coolant don't like each other, either. Looks like HPS makes silicone hoses. If you can't get a standard hose at a decent price (or want fancy candy-colored ones), that could be a good way to go.

Ah, that sucks. I assume those are glued to the glass, or otherwise a pain to work with. Guess you could paint the underside of the glass grey and pretend the shade's still up! Which seal is going to pieces? I ran without an outer seal (the one around the glass) for ages, and the inner seal (around the hole) did just fine on its own. I might have a spare off my parts car, can have a look for that if you want.

Know someone with a 3D printer? Listed for an R50, but looks right to me. Would need to be printed in ABS or better. My '95 had a piece of cardboard up there, held with baling wire through the attachment points on the glass. Worked fine. Didn't look great, but neither do the OE sunshades, thirty years on. I tried cleaning and flattening the sunshade that came with my '93. Went about how you'd expect. Ended up making a new one from a political sign and the plastic bits off the factory one. I like your console box!

Is the hose itself failing, or just leaking at the end? I ask because the steel lines the heater hoses hooked to on the VG33 I'm working on were rusted to absolute buggery at their ends. I don't know how they weren't leaking yet.

Good to hear you got it, and that it did what you were hoping for! That snap ring fought me on mine, too. Probably because I was using needle nose pliers instead of snap ring pliers. I added a little grease to the mechanism (one hub felt dry and crunchy compared to the other), but yeah, no need to pack them. Check the bolts after you've run it for a while. Seems like each time I have my hubs off, they work loose after a bit. I tighten them back up, and they're good from then until I have them off again. Probably just the gasket compressing.

LOL don't mind us, we're easily distracted by weird gearboxes.

The transfer case computer compares the front and rear wheel speeds, which is how it knows when the rear wheels are slipping. The non-VDS trucks monitor the front wheel speed from a sensor on the front output of the transfer. Basically it's watching the driveshaft rather than the wheels. In stock form (or with the hubs locked), this works fine. But it gets confused when the hubs are unlocked, because as far as it can tell, the rear end is going highway speed, and the front isn't. The service manual has a list of error codes that the transfer computer can throw, readable via Consult or der blinkenlightzen. I'd be curious to see what code they actually throw. Possibly code 6, wheel speed sensors? Computer sees improbable data, blames the sensors? Looks like it can also flash the light once every two seconds if it thinks your tires are mismatched, which could also make sense with the front/rear wheel speeds not matching up as expected. I would not be surprised if drag in the clutch pack spins the front drivetrain somewhat, but it must not be spinning at full speed, or the computer wouldn't know the difference, right? The electric pump doesn't run in 2HI. Otherwise it kicks on in reverse, and at speeds under 30 km/h (if I'm reading the chart correctly), when the mechanical pump (driven off the input shaft) isn't making enough line pressure to work the clutch pack. But yeah, this is all completely irrelevant to this thread if csprinkle's rig has the manual transfer.

Looks like 10-7/32" x 1-11/32", and the total across is 33-7/8". Measured in the dark, with a tape measure, in units the hood wasn't designed in, for maximum accuracy. Looking to return the R50 to its roots?

How did you connect the aftermarket radio to the Bose amp? I don't know the R50 sound system, but when I put a head unit in my '95, it didn't have a line-level output, so I wired the outputs of the HU's amp to the inputs for the factory amps. This did work, but it was not ideal, not least because it amplified the stupid beeps that Sony programmed into that head unit to an uncomfortable volume. I remember picking up some bass and mids when I got around to bypassing the amps. If you've got the amps connected to a line-level output, or a converter, then you're probably in better shape than I was.

Oil leaks can be a pain to track down. Valve covers are a good bet, though. Check and loctite (or have your mechanic check/loctite) the power valve screws while the intake is apart. IIRC there's an oil cooler on the VQ that tends to leak, so check that too. +1 for going straight to the service manual. The later service manuals waste a lot of space telling you what buttons to press on the special Consult scanner that you don't have, but there's usually real diagrams/troubleshooting if you scroll down a little. For the trans code, I'd start with the circuit test at the top of AT-151. Funny, my '95 had the harsh 1>2 shift too. My '93 has a softer 1>2 than it should. I haven't looked into it, probably an accumulator or something. Might be worth chasing if you drop the pan to go after that torque converter solenoid, but otherwise I'd let it be. Mine hasn't gotten noticeably worse over the past 30k miles, and I've got a replacement transmission waiting in the corner, so I haven't gotten excited about chasing the issue.

Locking hubs are for the front wheels only. Running with the hubs unlocked gives you a slight reduction in drag, because the front CVs, diff, and driveshaft aren't coupled to the wheels when they don't need to be. Unlocking them won't turn a Pathy into a Prius, but yeah, it should coast a little easier, and use a little less fuel. The trade-off is that you have to get out and lock the hubs to use 4WD. This is annoying if you forget about the hubs until you're already stuck. I use 4WD a lot in the winter, so I lock mine at first snow and leave them that way until after the thaw, so I don't have to think about it in between. Just remember to lock yours before you set off on those rare days when Seattle sees snow and you should be golden. 27 spline hubs are for the real early WD21s. You need 28 spline hubs. There's a comparison thread here for the various hub options, including which do/don't work with the stock wheels. If you've got the manual transfer case (stick through the floor), then that's all there is to it. If you've got the automatic transfer case (knob on the dash with an "auto" setting), then you may get a warning light on the dash after driving for a while with the hubs unlocked. Some info on that in this thread. TL;DR: the transfer case computer gets a little confused, but the transfer case itself doesn't seem to care.

I started taking pictures, then realized that was dumb because it's tough to tell which way the camera's facing when it's inside the wheel well. So I took a short video instead. Hope it helps. (Dropbox link)