Haha, too kind! And sorry about the delayed response...just completed a marathon 3-day truck overhaul for another R50 owner. Madness!
Ok, here goes (long post, heads-up)...
Everything worth knowing (specs, instructions, and parts info) is found in Propeller Shaft and Differential Carrier ("PD") section of the FSM. The most notable things are the specs and parts explosion. Best bet is to print the entire section for your mechanic.
The specs are found in the Service Data and Specifications (SDS) section towards the end of the H233B subsection. It looks like this (for a 2004 Pathfinder):
Somewhere before this in the PD chapter, you'll find either a full parts explosion for all the parts, or a smaller explosion like this (again for a 2004 Pathfinder):
BTW, for a 1997 Pathfinder, the LSD is listed as having 5 friction discs, 6 friction plates, 2 spring plates, and no spacer (per side). It specs at 65-80 ft-lbs.
Breaking down the parts:
1. Friction plate: stays stationary to the carrier
2. Friction disc: stays stationary to side gears
3. Spacer: some have a spacer that is equal in thickness to 4 plates/discs. It's just a big 6mm thick ring.
4. Spring: not shown in picture is a ring with a concavity. There are two of them per side (some older models only had one per); when the carrier is assembled, the spring plates will flatten and produce pressure.
The friction plates sandwich the discs, and when the torque differs between wheels, the discs twist between the plates to create friction.
Before ordering any parts, you should know the assembly order and thickness of each part...this requires disassembly. Note the list of part numbers above. Your LSD will consist of some combination of those parts. Most, if not all (except the spacer) will be 1.5mm thick. To thicken the stack, you simply replace the 1.4mm pieces (if any) or 1.5mm pieces with something thicker. The FSM specifies how thick that stack can be, so take note of your initial and calculated thickness. I found it easier to just find the nominal thickess (i.e., some will be 1.47mm thick, but treat them as 1.5mm thick) and see what parts can be replaced or rearranged.
The "optimal" ratio of discs-to-plates is 5:6...this is the arrangement that uses the max number of friction surfaces. It is not necessary to have that setup, since you can supplement it with thickness in some cases. If you need to bring down torque (in my case, where I was hitting way over 300 ft-lbs at one point), you can keep the same stack thickness and reduce the ratio to 4:7.
If you have 2:5, then you have the spacers and need to replace each with 3 discs and 1 plate. If you have 2:9, you need to replace 3 plates with 3 discs per side. Neither of these options are cost-effective, and might not be enough to get the desired numbers. Each disc/plate runs about $30-$35/ea from Nissan...it adds up quickly when you factor things per side. LSDs out of a WD21 will be a much better starting point. LSD parts for all H233B trucks/SUVs pre-2005 are the interchangeable. If using a WD21 diff, put your ring gear and side gears on the carrier, and swap it in. Of course, measure spec and see if it needs rebuilding (the FSM shows how to measure torque...may need to fab your own tool for measuring).
Dialing in the right amount of torque took me several tries. It really depends on the starting setup. I had to buy several pieces to hit my numbers, but I also started with a weaker LSD.
MY1PATH machined down some extra plates/discs as shims. That is another option if you have the means.
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On a parting side note, the vehicle overhaul done over the weekend included installation of a rebuilt 150 ft-lb LSD into another R50...the owner was very pleased with it. Mine also feels great.
Any other questions, feel free to ask!