I have been trying to identify my rear end without having to tear it apart. From what I see, it is probably not a 9" because there is no hump in the center section. The identifying numbers and tags are gone or worn away. Does anyone know what were the rearend options on a 67 GT???
These are the codes listed in the Mustang Red Book: 2.75=8(H) , 2.80=6(F), 2.83=2(B), 3.00=1(A), 3.20=3(C), 3.25=4(D), 3.50=5(E), 3.89=8(H), 4.11=9(I) The number(letter) can be found on the door I.D. tag.
I too have a 67gt, with a 390, so it should have come with a nine inch it has a “D” code in the vin number. However, the rear end does not have the “hump”. I don’t know why anyone would have changed it out for an 8in the car only has 50,000 miles on it, it was used as a summer car. Also at what rpm would the posi grab? At 2500 rpm or so in 1st it does a peg leg burnout but I just did one at 4500 and got 2 nice strips.
The early 9" rears looked like an 8" from the backside, the easiest way to tell one from another, is to see if you can fit a ratchet and socket on either of the two bottom carrier retaining nuts. If only an end wrench will fit these two, you have a 9. If you can use the ratchet and socket, it's an 8. Posi grabs at any rpm when you launch it.( if the clutch packs aren't shot) At anyrate your car should be 9" equipped with the 390.