Correct; the 10-1/2" Mustang clutch cover will work on the 351-C but the bolt pattern is wrong. So you either have your stock flywheel redrilled for the smaller pattern in addition to the stock one, or buy a Mustang flywheel. The balence factor is identical in all Ford flywheels (withing factory specs, anyway) so they are all bolt-ins, given the number of ring-gear teeth are the same (two choices here). Supposedly, Centerforce sells a 'Pantera-specific' dual-friction clutch p/n DF021048-S that bolts onto our stock flywheels, but I haven't seen one so call them first & verify this. This p/n is NOT in their current catalogue (the 'S' is missing).
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