Whether this car came originally with an 11-inch or 10 1/4-inch clutch is a mystery, but the one that was on it when it arrived here is an 11-inch clutch. All the catalogs list both, but seem to point to the 10 1/4-inch for an original assembly.
To make sure we got the correct one, NAPA ordered in an 11-inch clutch and it checks out.

