What do I need to run 3.73's?

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You mean to do it yourself, or as in supporting mods.

If you mean to do it yourself, you need basic tools including jack stands (of course). But more importantly you would need a dial indicator with magnetic stand, and a precise caliper to measure your pinion head and shims. And you should get a rear end rebuild kit.

If you mean what supporting mods do you need with the gears, well ... nothing. You may want a beefier torque converter and a shift kit. But you do not need those with just 3.73s. Think more about 4.10s.
With a rear that's a 100% you would only need a ring and pinon gear and a shim kit. Special tools would be a dial indicator and a magnetic base for setting the backlash. If you use Ford gears you can use the same shims on the old pinon gear on the new one and your pinon depth will be close enough. You would need access to a bearing puller and a press to install your bearings. You need an inch/lb torque wrench to set your preload on the pinon bearing.

Other things that you may want to do are to rebuild your traction lock unit and change the carrier bearings.

I recommend a shop to do this job. It's one on the toughest jobs to do on a car.
I went with the borhters speed cal.


My shop advised me to do this as I was watching costs and now I am bringing it back for a full rebuild (all 6 bearings and all seals). It is not worth it. I will lose my car for another day, but at least he is giving me a good deal on the labor this time around since it was both of our faults.

GRGT1994 said:
Tougher than rebuilding an engine bottom end?

I have done both and the engine isn't that difficult at all. Feeler gauge and a torque wrench are just about technical, as you need to get with an engine bottom. In the Hanyes' auto repair manual you'll most likely find the procedure for engine rebuilding, but not for differential service.

One of most diificult deals is to get one of our engines to a decent idle after a performance cam has been installed.
94-302-vert said:
I went with the borhters speed cal.


I'm not sure on that one...plenty of people dont do that.. high miles, yes I would swap all the bearings out..
I had 52k on mine...added 355's with everything re-used, including the same crush collar...ran that to 68k, swapped it all over again to use 373s...now at 72k its still dead quiet...
larryford said:
About going to 3.73 with my AODE. What I meant is the computer going to get confused about the difference in the rear gear??

thanks :D

no your computer has nothing to do w/ your read end as far as monitoring it. The only thing that will be off is your speed if you dont get a correct spedo gear.
igotyofire said:
im confused do u need a tranny gear and speedo gear or just the speedo gear?

I think some people are refering to it as the same thing but calling it 2 diffrent names. All I did was get the correct spedo gear ( which goes in down near the tranny) and my MPH are right on.