3.88 R&P differences

[911wrench]

Good morning to all. I am rebuilding a T-1 IRS SSC for the #54 JB Bugs 73 Super Beetle Chump Car Paul is building/rebuilding from a crash last year at Sebring.
It had a cracked case (the crash knocked the motor out of the car and broke the trans case) so I am swapping the internals over to a different case. It had a 3.88 Ring and Pinion that was worn out (pitting on pinion teeth) and this trans has stock 1-3 gear ratios with a .89 4th (3-4 gears are welded, coarse tooth). So I am replacing the R&P with a good used set, when I discovered that the 3rd gear (fixed gear) splines are smaller (by approx .3mm) than the pinion shaft I am beginning to set up. I have torn apart several other gearboxes looking for either a coarse gear 3rd gear set with larger ID, or a smaller OD splined 3.88 R&P set with no success.
My question is, what year/application 3.88 R&P with smaller splines am I looking for, or what year trans would have a coarse 3rd geared (I believe it's 1.26) with large ID splines? (or is this an aftermarket gear set)
Any help to point me in the right direction is appreciated, I'm just trying to get these guys back on track with a good, fresh gearbox.
Thanks, Scott Windecker.

[Pablo2]

Normal MO is to chuck the pinion shaft in a lathe, and OD-grind the portion of splines for 3rd gear just enough for the gear to smoothly slide on. I'm far from my service bulletins, but I can remember the bulletin ..

[911wrench]

Thanks Pablo, that did cross my mind. I'll give it a try. Have you ever drilled/tapped the main shaft for a bolt/collar to hold it, in place of the circlip?
Scott

[Pablo2]

All my performance transaxles use threaded mainshafts, but I usually deepen the circlip groove on my pinion shaft just a tad. Never bothered tapping.

[Henryhoehandle]

All my performance transaxles use threaded mainshafts, but I usually deepen the circlip groove on my pinion shaft just a tad. Never bothered tapping.

Exactly.. the grooves were barely deep enough from factory.