Ok I am 100% sure now that my stock 2.77 series 2 9 bolt did not have a pinion shim behind the head. Now I am moving to a series 3 carries and 3.91:1 gears. Do I just press the new bearing on the new pinion without a shim since the old on didnt have one eighter? The use making compound and check the pattern?

 

you should meaasure and set the pinion depth to the gear makers spec. it's differant for each gear set, or could be differant, that's why a shim is used. hone your old pinion bearing out so you can slip it on and off without needing a press each time you change shims.

 

yea I dont have this pinion depth spec since I bought the gears from diffsolutions

 

Nine times out of ten if you mark each shim and spacer from the gearset you are replacing and put them back in the exact same order when you install the new gears it works out okay. Make sure the pattern is good as this is the most important aspect of the swap. Next make sure the backlash is okay... not too tight and not too loose. Here is some helpful specs https://www.thirdgen.org/newdesign/t...tservice.shtml