Slartibartfast

Should be multiport if it's a '94. Runs fine otherwise?

+1 on a clean install! Looks like the same lights I used. Hopefully yours are waterproofed better than mine were. I mounted mine to my '93 in the same place, between the bumper and the hitch. Nice and hidden, both visually and from whatever I might happen to back into. Looks like the QX4 tail lights have reflectors built in. That could be another way to go without highlighting the hitch with tape. That said, the Pathy lights look a lot better IMO. The license plate's reflective, right?

My first thought is that the timing does change a bit as the engine warms up. If you're checking it cold sometimes, and warm other times, you might be chasing what the computer does normally. Then again, I doubt you'd be digging into this if the truck wasn't running weird. If it's actually moving, and in the same direction each time, I'd pull the dizzy, see if it spins freely, and see if there's anything obviously wrong with the drive gear. I'm pretty sure the drive gear's just pinned on, and if the pin has failed, the drive gear could be slipping on the distributor shaft. Maybe the distributor bearings are going out and each time they catch, the drive gear slips a little? The only other thing I can think of is a slipping timing belt, but it sounds like you've adjusted the issue away multiple times, and I doubt the engine would be running at all at this point if it was skipping a tooth at a time on the crank sprocket.

My '95 just had a light that said "tire carrier." Guess Nissan decided that was too complicated. Or they realized that their logo kinda looks like a hamburger, and thought they'd just roll with it?

Two in one day? That sucks. I've mushed mine a couple times, once on a ditch (damn thing jumped in front of me!) and once on a deer. After the ditch, I pulled it and beat it straight and had a hell of a time getting it back on; after the deer I knew better and just straightened it with a strap and another truck. It's a little cockeyed but it'll do until I get around to building a bumper that doesn't fold back and bite the fenders whenever it's whacked. +1 for wreckers if you can find one, but these mush so easily that you may have trouble finding a straight one. A black one is about $40 on Rockauto.

Ford had a thermostat bypass for the trans coolers on later Crown Vics. Sounds like it was more trouble than it was worth; marginal benefit when it works, overheated tranny when it doesn't. I've got mine plumbed with an aftermarket cooler in line with the stock one, the same as your Q apparently. It's a fairly new rad so I wasn't worried about gunk, and by the time the slushbox pukes up enough material to clog a cooler, arguably the cooler's the least of the system's worries. I've never bothered to hook up a temp gauge for the transmission to see how much good this setup is or isn't doing.

Manual hubs from the D21s bolt up and are supposed to be pretty good. There are also aftermarket options as well, not sure what's available in your area though. I'm running Mile Markers on mine which have been great except that the chrome plating on the rings didn't last long. The trouble is that Nissan had two different spline counts for hubs, 27 or 28. Count the splines on your CV axles and find hubs to match.

I've heard of "fail safe" thermostats that lock themselves open if engine temp goes above a certain point (and tend to lock up for no good reason). Seems odd that a new thermostat would've failed already otherwise. I'd want to check the temp sensor and the temp gauge before taking it all apart again.

Those bulbs in the first pic look like the wedge-base bulbs my friend picked up for his Chevy instrument cluster. I think he got them off eBay. They lasted a while, then the chips crapped out and started flickering and we put the 194s back in. I've got little fleabay LED panels in my dome lights that have held up great. I went for the warm white, and not the largest I could fit, after fitting the largest cold white panel I could in my '95 and just about burning my retinas out when opening the door at night. Looks about like the stock bulbs, but doesn't kill the battery, which is what I was after.

Sucks when it's time to fit it all up and something's that little bit off. Should be nice once you've got the bugs out, though. What's the fan by your distribution block for?

You can get the factory manual here--download the '94 or '95 ST section. The manual's for a US-spec truck but I'd expect it's got the same steering box.

Nice, they finally made a metal-cased version! I've got the old plastic style on mine currently.

I've read that the clutches in the limited slip don't grab properly with synthetic lube. I have no way to confirm this, but will probably use conventional oil when I get around to it.

Putting it on the outside might do something, but I suspect it would be much less effective.

Good luck! Keep in mind there are different variants of the speed sensor with different sized drive gears to suit different axle/tire combos--at least there are for WD21s, I assume R50s are the same. The gears are color-coded.

Looks like the speedo should be on the side of the transfer case (assuming 4x4), towards the back. There's a picture in this writeup with the speed sensor pointed out.

Symptoms sound like a booster. I don't know how much vacuum the booster gets, or even where it comes from on the diesel trucks (I assume there's a pump?). I would unhook the vacuum line from the booster and check to see if whatever supplies vacuum is doing its job.

Also have a look at wiring for pressure switches and whatnot. I remember I somehow switched a couple plugs (one of them aircon related) on my friend's van when we were putting it back together, and the aircon didn't work until my friend figured it out. Hopefully Nissan didn't do what Chevy did and put two identical plugs next to each other.

Yeah, that ain't right. Seems like a control thing rather than a tranny thing, though.

Hmm. I'd start by checking your fluid level again, just on the off chance it burped a little air out or something. It sounds like it's shifting hard sometimes, soft sometimes, and not always at the right times, which makes me suspect the TPS might need adjustment or might not be reading properly. I don't see anything about a relearn procedure in the manual, but you might try unhooking the battery for a bit in case the TCU has some stored memory of the old tranny that's confusing it now. Is it giving you any codes? I don't know what to make of the 4WD light coming on, that's just weird. My best guess there is loose wiring, or the shifter bumped something when the engine downshifted (how are your engine and trans mounts?), but I don't see how that would've pushed it back far enough to turn the light on.

This is the thread for WD21s. I'm running 5W30 in my engine (Valvoline high-mileage synthetic blend, mostly because it was cheap), generic parts store dex/merc in the auto trans and the transfer case, and I still need to get around to changing the fluid in the diffs.

If the rear wiper's set up like my '93, there's a rocker switch on the dash (to the right of the column on mine). Not sure if you've got the right hand or left hand drive dash though, or if that changes the control layout. Can you follow the wires from the fan to the resistor pack?

If you're not sure which is which, you could probably unbolt the seat and push it up, or flop it forward, or just use a mirror or something, then work each adjuster and figure out which motor spins for each. Looks like the mechanism is exposed enough for you to see which ones are or aren't moving. That should narrow it down to which one's borked, and it looks like it should be easy enough to pull that motor and have a look on the bench to determine if a little percussive maintenance will bring it back or if it's time to track down a replacement.

Too bad the cap didn't do anything to the code, but good work finding the actual cause! The audio cable would probably work fine, provided you can ground the shield, but there's probably an easier and cleaner way. If the mushed section isn't too bad, I'd be tempted to repair the wires, pull the shield back over if it's not completely severed, and heatshrink it all down. Looks like you can also get wire shielding tube on its own in various sizes to go over whatever wire you want to use.

The joys of brittle old trim clips!