9 inch

I had to study up on how to identify a 9 inch rear end over an 8 inch. The clue I was given is that the two bottom nuts on the very bottom of the carrier cover are not accessible with a ratchet so the two fasteners need a wrench to get to them. Here’s a little video that gives some pointers to help differentiate the two.

Like everyone who gets an old car that belonged to a performance heritage, I was hoping that mine had the performance rear end. In Chrysler, it was the Dana 60, GM had the 12 bolt and Ford had the 9 inch. To the uneducated, the 8 inch Ford has a strong resemblance to the Ford 9. You have to know what to look for to identify it properly. I was not educated so after learning what to look for, I confirmed that this Mustang was graced, from the factory, with an 8 inch.

I didn’t want to jump on the 9 inch band wagon just because all of the cool kids had one, if the diff could handle moderate power, I’d stick with it.

Without going into a lot of detail, I decided to look for a 9 inch.

I didn’t want to pay for shipping so I kept my search local which meant Craigslist. It didn’t take long. I found some guys in Anaheim who buy old Mustangs and part them out. They had a 9 inch, drum to drum out of a 70’ Mustang. Perfect. No modifications to make it fit or convert to leaf springs. It would be a straight bolt in. Highway gearing and it was a peg leg. I called the seller up. He still had the rear end. I made arrangements to meet with him and look over the housing. Two days later I’m in Anaheim and the piece looks great. I bought it and took it home where it sat for a few years until I was ready to put it to use.

While the Mustang was in time out I wanted to catch up on a few other aspects of the build so I started looking over what I needed for the rear end.

I pulled up the internet and starting shopping around. I was looking for a Nodular iron center section and something in a posi. I found an ebay auction for a third member, Nodular case, Detroit Locker and 3.5 gears. There were other offerings but this one seemed the best deal so I bought it. When it showed up, my plan had been to get all of the pieces together and take them to S&J gear in Huntington Beach to get the housing and differential checked out, new axles, etc. Plans change. The third member showed up and I got busy so the diff went into one corner and the housing into another.

I would be several years before I came back to the 9 inch.