Is the rear end stamped CW or CE? CW is a 3.31 open 12-bolt that has been found behind 396 engines, both 325hp and 350hp, as well as the L48 350/300hp engine. The CE rear end is a 3.08 indicating a 10-bolt and wouldn't be used in an SS car.Kind of depressing, but the code on the rear end is a CW. The bad news is it's not a Posi, the good news is it was a rear end that went with the 350 Horse engine that I suspect was in the car with the Tach redine at 5500.
Edit: Maybe someone can help me out, I misread the 350 for HP instead of Cubic Inches. Could you have a 350 horse engine with a CE rear end? Did a 5500 redline indicate a 350 horse engine only or did it work with a 325 horse engine as well?
Casting numbers on 12-bolts are 3917124 (early) and 3959038 (late) and the 10-bolt is 3859037.
The 5400 redline tach is listed in my parts book as being used in all 396 except special high performance which I take to mean both the 325hp & 350hp engines.