[Nelz_66]

Hey there…I’m converting a 66 Mustang Coupe from a 6 cylinder to an 8 cylinder. The car came without the original rear end. I was told that it had a 9 inch rear end in it, but from what I’ve found out, its looks like an 8 inch with a Daytona Pinion Support. What I haven’t seen though is how much horsepower and torque that the 8 and 9 inch rear ends can stand up to.

[68 Coop]

I wouldn't go much more than 400/450 with the 8, but you could build the 9 to take almost anything you can throw at it. See if this helps figure out what you got for sure.

http://kevinstang.com/Ninecase.htm

[1qwk67]

I have right at 400 hp in my 67, and so far the 8 is holding. I put an Auburn posi unit in and Richmand 3.55:1 gears..