Glad you guys found this useful.
At some point since my last post, I had finally received a new-old-stock full 3rd LSD member I had ordered earlier in the year...completely unused, never-installed housing, gears, carrier unit, probably sitting on a shelf for the last 25+ years. Took it apart to check the setup, cleaned and lubed the parts, then gave it a test. It peaked at 307 ft-bs (actually, it peaked at 330, but I discarded it from the dataset), averaging around 298 ft-lbs, and with the "optimal" 6:5 setup and the older spring plates (with tabs) and spring discs. (Realizing now I should've taken pics of the spring plates.)
I owed a buddy a rebuilt LSD for his 99 Frontier, to replace one I had repacked a few years ago. It was still holding up, but he felt it wasn't grabbing as well as it used to (I think we had it around 180 ft-lbs, but my testing method at the time was far more primitive). Plus, he had recently supercharged his truck, so a little more grip would be nice. Rather than give him the 300 unit with bunch of nice unused pieces, I swapped in some "A" grade used pieces and changed the setup to 7:4 to bring it down to 250 ft-lbs. He hit the trails with it over the weekend and said it made it a big difference. (We also took the truck around the block after getting the LSD in...and man, that supercharger makes a huge difference in that truck!)
His old unit was reading about 80 ft-lbs when I tested it his place, but I later took it apart, cleaned it all out, and noticed that the springs were series. Put them back to parallel (he mentioned he may have flipped them at some point) and it retested around 165 ft-lbs. Not sure why there was such a large change from flipping the springs, but may have also been a residual film on the pieces, perhaps from old or dirty oil. The pieces cleaned off well and looked to be in good shape (I used some new pieces originally), so I think freshening up the pieces played a part (I didn't shuffle them around, either).
Anyway, I ended up reusing this carrier for my Frontier LSD. After trying a few configurations, I'm going with an 8:3 setup that yields 105 ft-lbs. Since I have so many spare LSD pieces, I put the junkiest of pieces and a few 1.4mm pieces into the setup, too. I'm not sure what's a reasonable setup for a 2wd street truck. To that front, I have also acquired a D21 V6 2WD H233B axle w/ 3.9 gears and WD21 disc brakes to swap into the truck. Figuring to start that project this month.