I have a set of 3.58 gears from a wrecked '57 Special with a manual trans that I'm thinking about using. I thought I might try and do a posi at the same time if it would work. I don't know much about posi-traction, so I have a couple of questions: 1) I think that posi was an option starting in '59 and that the carriers interchange for '57-'60? 2) What gear ratios were available with posi? I think auto trans cars came with either 2.78, 3.07 or 3.20, so that seams most likely what you would find. Manual trans cars had 3.58 for '57-'58 and 3.58 or 3.91 for '59-'60, but were they available with posi? 3) If I found a '59-'60 posi unit could I use my '57 3.58 gears with it or are the posi gears different? 4) Are the axle shafts or anything else different for posi vs. open rear ends?
By how is it, do you mean the condition or how is it mounted? Condition wise it is useable and I will also be swapping that in. I will install it using the stock Buick trans cross member. I got most of the 3-speed specific parts off of that car, plus some more from another car.
Buick had a posi option starting in '56. I also have a 6 bolt top cover tranny from a '56 Bolt in & go.
Fortunately I have three '57 transmissions plus most of the gears out of a '56 and some NOS '57 gears as well. So I'm good on that. Is there a way to identify the posi units for '56-'60? I know the gear ratio was stamped on the bottom of the housing but what about posi info?
Yes, I would be interested in that. Find out if he knows what gear ratio it is or if gears from posi and non-posi rear ends interchange?
