[Don_Lightfoot]

Was 3.55 the standard ratio on an SS454 manual transmission car? If so, then I would say the 3.55's would be correct for a car where no "performance" or "economy" ratio was stipulated on the new car order form. Posi was an option on virtually any ratio.

If I recall, I'm sure I have seen LS-6's, let alone LS-5's, advertised with M22's and 3.31 rear end. All in the hands of the person putting in the order.

Just my two pennies worth.