Ring and pinion set up question

[Greg Reimer 7376]

Back in the bad old days,I was a line mechanic at a few Chevy dealers. There were still quite a few 12 bolt equipped cars running around out there then, and it seemed that the lower the gear, the thicker the pinion shim needed to be for a good set up. OEM stock gear ratios, 2.73-3.73's seemed to like a .030"-.031" shim, 4.10-4.88's all seemed to like an .032" shim,5.38's and 5.57's seemed to need an.032-.033", and insane ratios like 6.14's might want an .034-.035. .008-.011 on the backlash seemed to be optimal,as well.You are right in the center of the infield with the dimensions you mentioned, but you didn't state what gear ratio you are using. This info should get you started.