Ok so im getting a new rear axle for the heep and have decided on a Ford 9 inch. I found one in my area for $100, not bad considering its already pulled out of the veichle. Anyways to my question..... I know not all Ford 9 inch rear axles are the same. There are many differences between spline count to width and whatever. This particular axle I found is out of 1962 ford truck.... Thats all the info I could get out of the owner. Im afraid this axle is the small bearing, 28 spline version that came in earlier models but I'm not sure. If there are any Ford 9 inch guru's out there that know about this particular axle from that time period any info would be greatly appricated, thanks ya'll

 

A small bearing housing can be differentiated from a large bearing housing by the size of the thread pitch used to retain the brake backing plates to the housing, the small bearing housings use 3/8” fine thread, while the larger bearing use 1/2” fine thread. Hope this helps also heres a pic of the different housing ends

 

look it up online

 

wow thanks for that great advice.... What do you think I've been doing.

 

also from what i remember is most of your truck and big car housings are 31 spline but the 66-70s bronco were 28 spline

 

Most trucks up to the early 70s had 28 spline but that's an easy fix. Weakest part of a 9" is the factory chunk. I got a buddy that's running one from a late 70s Mercury car in his wrongler with the stock 28 spline shafts and 36s and it's holding up just fine.

 

ok, thats cool he's running the stock shaft with 36's, which is what I plan to run. Can't the small bearing, 28 spline be ungraded to a 31 spline?
Anyways you guys think this is a worthy swap to get rid of my Dana 44a?

 

You can upgrade up to 40 spline but it's a bit overkill and way pricey. I'd go 31 or 35 for strength and aftermarket support.

 

to my understanding you can only upgrade a small bearing 9 inch to a 31 spline. Its the big bearing models that can upgraded to a 40 spline... Is this correct. If this is true I think I might get the axle I found, even if its a small bearing model because its only $100, and then upgraded to a 31 spline shafts. that should withstand up to a 36 inch tires, thoughts?

 

I'm thinking you may be right. I know my uncle runs 35 spline on a drag car and I think it's a car housing which are typically small bearing but all I can find is 31 spline. That being said 31 spline will be plenty strong for 36s especially with what little power Jeep motors make.