Welcome to the Team Roger!
PosiTraction was a very rare option back in 1964. Any Hotchkiss limited slip clutch style case will have a big "P" cast onto the drivers side of the case, and a price tag of close to a $2,000 or more. This is because early straight axle Corvette owners think that their 1953-'62 'vette should have a posi also; but there were just so few made. They will pay through the nose for a P case, driving up the price of those found on e-Bay to the point were it costs as much as a new Impala project car.
Additionally; that same Salisbury rear end designed and built to last a life time in a car that was powered by a 235 six (that was used in all Chevy's back before the first V-8 came out in 1955) is not going to last long behind a high horse V-8. That is why Chevy dropped that rear end in 1965 and went with a Spicer rear end made with stronger components.
Those rears broke so frequently that having one replaced is not only a common occurrence, but expected when found in a high performance car with a manual tranny.
Last edited by Big Dave; 11-13-2013 at 03:07 PM.