Nine inch question

All nine inch chunks are fully interchangeable in the housing. Only difference is the axle spline count. $200 is more than reasonable for what he's got. Altough you can still find 31 splined trac-loc rears in full size Broncos for less. I paid $150 for a complete 9 with T/L and 3.50's a year or so ago from an 81 Bronco.

Forget the Bronco. It would cost a lot more to make it work than to use what you have and add a trction lok.
Not all 9" center cases are small bearing, but your 70 most likely is. $200 for a bare traction lok unit is a fair price Not a killer deal, but a fiar price for a used part. They can be bought new for about $325-350.
Any 9" third member would bolt into your housing. There are two different spline counts for the axles (28 and 31). That part shouldn't be hard to figure out. There are several different driveshaft yokes and u-joints out there, so you have to make sure you have the one that matches your driveshaft.

04mustang70 said:

What about the bearing size? Does that matter or doesn't it matter what size the trac loc bearings are? Does my stock rear end have the large or small bearings?

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I'm asuming you're talking about the carrier bearings, in which case I think (not 100% sure) that as long as you've got a 28 spline case and you're going back in with a 28 spline, you're fine. As for what year Bronco, it doesn't matter, all 9 inch center sections fit in all 9 inch housings. The difference is you may end up with a 31 spline unit in which case you'll need to upgrade to 31 spline axles (which is a plus as the axles are bigger and stronger than what you have now) Most Ford 4wd trucks and Broncos had a traction loc rear. One look at the id tag (these are bolted onto the carrier housing with one of the nuts holding the carrier in place) will tell you if it's a T/L unit. The gear ratio is stamped there with an "L" in the middle of the ratio (as in 3L50, 3L70, etc)

As Dhearne said, you can replace one 28 spline carrier with another. Any Ford 9" carrier will bolt in place of your existing carrier, thus the traction lock will interchange into any Ford carrier, even a peg leg like you already have.

As far as bearings, as you have found the Ford 9" cases are built with 2 possible sizes. 2.8xx" and 3.0xx"--the exact size isn't important as long as you remember the #'s given. These are known as "B" cases and the guts are fully interchangeable but you must have the ones with the same spline count as the axles you are going to use. The carriers used in the cases are still the identical same ones and you can swap them into either case with a simple carrier bearing swap.

With a stock Ford case you cannot use the Nascar inspired 2.250" bearing "H" stuff that is often found cheaply on egay. These are strictly aftermarket pieces and require an aftermarket case.