I don't think that will help John,as all three 4 spd. transmissions behind this Chevelle could've received a 3.31,3.55,3.73 or 4.10 gear back then from the factory.
I suspect someone swapped in the rear axle tube afterwards,who didn't have access to that partial buildsheet,or if they did,they weren't savvy to noticing the G80 & G84 notation of 4.
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