The Stovebolt Site Forums The Shop Area Engine Shop 3:08 And 3:73

I want to update the front axle in my 64 4x4, to an open knuckle & Disc brakes. I have a 1980 1/2 ton donor truck with all the parts I need, steering, MC, Etc. My question is, the 64 has 3:73 gears, and the 80 has 3:08 gears, is anything internally interchangeable between the two axles? or should I just look for a truck with the correct 3:73 axle that I need? Thanks!

If you have a matched pair from the donor change them both, with the brake booster and propotioning valve from the donor the brakes should work fine. Also the 308 gears should help the MPG.

Sorry if this is not relevent, but if you are changing just the front axle on a 4wd. won't this be a serious mismatch of ratios?

In theory you could match up your ratios by changing tire sizes,but that's a real bag-o-snakes to get into. You can swap a set of 3.73 gears into the newer axle,but it won't be cheap. Best option would probably be to use a wrecking yard hotline and try to find the kind of axle you want with a ratio that matches your other axle.Or if you want to go for the 3.08 ratio,go for a donor truck and use both axles. If you go this route,don't forget to grab the speedometer gear too,if it's available.
Speed

Thanks everyone! Sounds like I'll look for a 3:73 donor. This ratio works good with the 292, and I would like to pull my trailer a few times a year with it. ttodd, you are right about the gas mileage, I have 3:08 in my 71.