IRS adapter

[Sigurd]

I just installed the driveshaft adapter to the FF supplied IRS diff. The gold colored one for the manual trans does not fit, to large diameter. The aluminum colored one does, both to the diff and on the driveshaft.

Can I assume have received a diff that was originally intended for a car with an automatic transmission? If so, are there any differences other than the input shaft?

Comments?

[edwardb]

Ford uses the iron case diff on manual shift Mustangs, and aluminum case on automatic trans Mustangs. Both have an aluminum back cover. The iron case and aluminum case diffs each take a different adapter, but other than that, everything else is the same and should mount up OK.

[PaulProe]

I have seen indications that Ford has changed the pinion flange on the cast iron style. Measures the same diameter as the automatic flange. Haven't been able to confirm if it is a Ford assembly error or if it is, in fact a change.

[Sigurd]

I have seen indications that Ford has changed the pinion flange on the cast iron style. Measures the same diameter as the automatic flange. Haven't been able to confirm if it is a Ford assembly error or if it is, in fact a change.

It looks like I have one of the newer rear ends, cast iron with the flange that measures the same as used on the automatics. The adapter fits perfectly in both ends.