Is $100 for a complete 9" rear a good price? It is a open diff with 3.00 gear ratio. I am still waiting on the spline count of the axels. I was planning on buying a spool and M9 housing kit for my camaro but I figured the center section for $100 isn't a bad deal.

Thanks,
Chas

 

I pulled a complete center section out of a Bronco years ago. Case, gears and 31 spline posi cost me $100.

Along with the spline count, find out what the case casting number is. Most common is the C-7AWE case. Even finding an old N case isn't worth the money with the availability of aftermarket parts now.

 

Do you know off the top of your head what vehicles I could pull a 31 spline 9" or 8.8" center section out of?

I also have an in on a 8.5" 10 bolt out of a 79. It already has 3.73 richmonds and brand new eaton.

Which would be easier to modify to fit the thrid gen?

 

8.8 doesn't have a center section. It's designed like a 12 bolt.

The list is huge as to what a 9" can be found in. Do a google search to find out how to determine if it's an 8" or a 9" and how to easily identify if it has 31 spline axles or not.

None are "easy" to modify into a third gen. With the torque arm suspension, it's always difficult to find a way to attach the torque arm. Currie sold a mount that could be welded onto the 9" steel housing which allows the torque arm to be attached. All the other diffs like a 10 or 12 bolt and the Ford 8.8 have a cast housing which makes welding onto very difficult.

The easiest and cheapest way to put a better diff under a third gen is to order a 9" housing package. It comes with a housing and axles designed to bolt right into a third gen. Order it with 31 spline axles then go looking for a 31 spline center section from the junk yard and drop it in. The 9" housing package is around $1000.

Junkyard diffs come in many different widths. If you find one close to a third gen width, the cost of modifying and fabricating to make it work could cost more than just buying a direct bolt in one.

 

I was able to narrow it down a little and the 97 ford explorers came with the 8.8" that measured 59-1/2" flange to flange, 31 spline axels and posi/lsd. I know some of the older (89-93?) f-150s had the 8.8" rears but only a select few and the majority were open diffs with 2.70 ratios.


Would it be worth buying brackets and welding it onto a 8.5" rear? If I can find brackets.

 

Trying to weld mounting brackets onto a cast diff housing is difficult. You have to heat up the metal with a torch before welding and all that extra heat can distort the case. If you don't get proper penetration and a good weld, remember, you're trying to weld to cast, the mount could break off the diff which could case an accident.

If you want to use a chev 8.5 or ford 8.8, there's a lot of fabrication required to make it work which could cost a lot more than the price of an aftermarket diff. The other option is to completely change the rear suspension to something like ladder bars to eliminate the need for the torque arm.

It's that torque arm that makes swapping in a better diff very difficult.

With enough time, money and fabrication skills, any swap is possible. Don't expect it to be an easy or economical conversion.

 

Ya the torque arm is what I keep coming back too. My fab skills aren't too bad but I am no pro.

 

If you search through the TGO archive, you can find many posts on fabricating some sort of mount. There was a huge thread on installing an 8.8 a while ago.