[blykins]

If it's truly a limited slip/positraction differential, it's probably just a standard Trac-Lok differential from Ford.

If it's a McLeod diaphragm, it's probably a 10.5" clutch. I can't really say with certainty what kind of disc is in there, but if I were providing the parts for a slightly warmed over 351W Cobra with street tires, I'd just go with an organic/organic disc. Depending on how wild the cam is and well the heads are ported, it could be closer to 500 hp and then I'd recommend a dual friction (organic/bronze or organic/kevlar) disc.