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davepl · 03-24-2018, 12:48 PM

I'll tell you the ones I know, perhaps others can fill in the empty spaces:

GM 10-bolt car: 3.07 12/37 3.08333
GM 12-bolt car: 3.08 40/13 3.07692
GM 12-bolt trk: 3.08 40/13 3.07692

So that leads me to believe the cars and trucks are the same ratio, at least they have the same tooth count. I'm getting the truck numbers from this Yukon gearset for the GM12T-308:

https://www.summitracing.com/parts/yga-24459

03-24-2018, 12:48 PM	#33
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: 3:07 Rear End I'll tell you the ones I know, perhaps others can fill in the empty spaces: GM 10-bolt car: 3.07 12/37 3.08333 GM 12-bolt car: 3.08 40/13 3.07692 GM 12-bolt trk: 3.08 40/13 3.07692 So that leads me to believe the cars and trucks are the same ratio, at least they have the same tooth count. I'm getting the truck numbers from this Yukon gearset for the GM12T-308: https://www.summitracing.com/parts/yga-24459 __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible