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help decode my 12 bolt..

1518 Views 11 Replies 4 Participants Last post by  Dan1979
just picked up a 12 bolt open drum to drum for 300.. Real nice no rust at all. I already determined its a 69 rear but can't figure out the other #'s . They are R8 0903K. Any help would be great.. Also how do i figure out gear ratio thats in it? Is there numbers that tell that?... Thanks....Dan
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It is probably a 2.56 geared Chevy 12 bolt. R8 shows to be a 2.56 gear for the Oldsmobile type 12 bolt and they may have used the same code for the same gear ratio on the Chevy rear. On the O type 12 bolt it has a 12 bolt cover that is smooth with no eyebrow at the top and the ring gear is actually a 10 bolt.
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