Michael,
the only thing I can confirm is that the differential is a limited slip differential from Salisbury, of course then with different gear ratios as it was specified. Further Specifications I do not have. I was looking in an old Autokraft sales flyer and it did say Salisbury limited slip differential.
This I found on a Jaguar and a Cobra Forum, independently:
From 1976-1985, the differential was a Salisbury 4HU Power-Lok that came with either 3.07:1, 3.31:1 (1976-1982), or 2.88:1 (1982-1985) ratios.
Maybe this can provide the answer you are looking for?
Heinz