Jim,
Definately do NOT use 80/90 EXCEPT in the rear end! If you change that be sure and put a small bottle of the ugliest smelling stuff there is in it. Call "Ford friction modifier".
Tcrist is right, look at the back side of the pumpkin, if there are bolts around the edges it is an 8.8. If the bolts are on the front side it is a 9"--but very rare if any were used by CR's unless specifically ordered with one.
DV
ps. take a look on the last page of cpteddies/DV's build, there is a picture of the rear sway bar on the car and you can see the 9" in that one.
Here, this was just as easy. This is the rear of a 9' Ford housing....
