Mopar Action On-line – Tech Questions


Tech Question

jay scott, jackson, TN, 70 Plymouth Satellite 318

I have a 3.23 Sure Grip rear end and its a 8¾” housing (itunbolts from the drive shaft side). My question is what faster gears can Iput in there? Note that it will be mostly driven in the city and rarely onthe highway. I was thinking 3.55 maybe even 4.10. Am I able to to do thiswith just replacing internal gears or what? Thanks


Jay, it depends what carrier casting number you have. If your has a numberthat ends in “742” (1¾” pinion stem) or “489” (1-7/8″), then there’s noshortage of aftermarket gearsets from 3.55:1 on up (numerically). Thegearset installs quite easily if you have the proper tools and knowledge.(That’s a big IF, however).

If yours is the small-pinion pig (#741, 1-3/8″), then you have two choices:

Swap the whole pig (any 8¾” pig will bolt in).

– or –

Find some used gears. There’s nothing in the aftermarket.

I’d be remiss in my duties if I didn’t make a comment on gear ratioselection: Assuming that your 318 is stock, or close to stock, it is tunedas a low-RPM “torque” engine. Frankly, I think even 3.23 migh be numericalya bit high!



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