So I went out on a whim and bought the Truetrac for my 93. Set up nicely, but ran into a few things. The spline length in the side gears are too long to let the snap rings in the axle stubs engage (disappointing to say the least). and obviously the carrier bearing journal inside diameter is too narrow to accept the needle bearing eliminators (bushings) from ECGS. I was going to chance it and run the diff without the bushings and see what happened lol. But upon assembly i installed the axle stubs and per the directions from the FSM, checked snapring engagement by attempting to remove the stubs by hand. Both sides came out with relatively little force. So after a bunch of trial and error, I confirmed that the spline length was too long in the side gears of the truetrac. I've read on the 3rd gen runners that this was solved by machining a relief groove on the outer side of the splines on the axle side, however personally, I rather would not weaken the axle stubs (minimally, I know) and remove material from the side gear instead. So I disassembled the truetrac and sent them to a buddy who's a former machinist and has a smaller benchtop lathe to bore out the journals to accept the bushings and remove just enough spline material from the side gears to let the snap rings engage, long story short when he tried to bore out the bearing journals and remove material from the side gears, he fount out that both were hardened to the point that his lathe did not have enough torque to cut into either the journals. I called eaton about the issue and spoke to one of their engineers and obviously wont do anything to modify their design to fix either one of these issues. So, I called 10+ auto machine shops and Front Range Driveline in the Denver area and all of them would not touch these parts. My question is, does anyone know of a machine shop (preferably in the Denver area but I am willing to ship) that may be able to do this for me? I don't mind paying whatever it costs to get it done because its still cheaper than an ARB and i would rather have the aid of a limited slip since my rig is a daily. I have included the pics of said parts and the part number of the TT for anybody wanting to do the same thing so they do not run into the same problem I am having...

Hub Journals on the left. Side gears on the right. I.D. of the journals needs bored out to accept the bushings from ECGS and the side gear spines need shortened from the inside part of the side gear (material removed from the side facing the inside of the diff, The side gear closest to the bottom of the pic)

Part # of the box the diff came in

Part # etched on the diff itself

 

Wow this is really sad to read. I stumbled across this while searching for answers as to why my Truetrack setup doesn't seem right. I wish I could help with your situation.. If you dont mind answering a question for me, how close was your TT shim setup compared to the stock carrier that came out?

Edit: this is for a 1988 v6 front diff (but had the 45mm ID carrier bearings, so I had to upgrade to 50mm for the trutrack according to ECGS)

I ordered my TT from ECGS in Feb 2021, they did their machining and sent it out along with a shim kit I purchased to help with the install incase it wasnt close enough to my stock shims. Well its not even close.. I can fit an entire extra shim on one side, obviously its not close to correct backlash, but I cant understand why I have an extra 100 thousandths space to fit another shim in. Using two of the largest shims is not close to getting anywhere near enough preload, and using two of the thinnest on each side is too wide. Is there such a thing as a "fine tuning" shim kit that you can get, allowing you to stack multiple shims together? This is the only way I can see it ever setting up properly. I have tried to call ECGS twice about this but they never return my calls.

Thanks buddy.. hope you get yours figured out.

 

Having the same issue as OP and have been doing some digging. Eaton's website lists 2 possible part numbers for 7.5 in diff applications - 911a445 and 911a342. The 342 is supposed to work for 3rd gen 4runners and the like, and the 445 is supposed to work for 95 4runners and earlier. This is according to the Eaton application .pdf from their website. - (https://www. eaton.com/content/dam/eaton/products/differentials-traction-control/eaton-performance-differential-application-guide-en .pdf)

I've spoken directly with Eaton, and they weren't sure. I've spoken with West Coast Differentials (who supplied the part to my differential guy) and you know a lot more than they do but the support line at West Coast Differential says they only sell the 342. All of which is to say, I've reached out to Eaton via email this time around, and am hoping to get a more accurate response. I will update as I find out more information.