I have a 12 bolt olds bop rear in a 72 skylark. Or atleast thats what I was told. Im currently slapping a 400 th tranny w/ 350 motor, until I get my 455 built. Is it cost efective to make this olds rear a posi. Or look for a chevy 12 bolt?
Sounds like you have a '67-70 type "O" Olds Cutlass or 442 rearend. This rear was only used by Olds & will have a smooth 12 bolt cover & have bolt-in axles. If your happy with the gear ratio, say its a factory 3.08 or 3.23 singletrack, one can buy a modified Ford 8.8 trac-loc carrier for near $500, & have it installed. Good ratio factory Olds Anti-Spin carriers for these are tough to find, thus the mofified Ford posi carrier route. Over the last 15 years, I've rebuilt five 31 spline type "O" factory 3.42 & 3.91 Anti-Spin rears. Also half a dozen 3.08's & 3.23 Anti-Spins. None of these racked up huge expense as the posi carrier (to be rebuilt) & desired ratio gears were already there. On the other hand, if the factory gear ratio is too high, IMO, the type "O"s are really not worth building up, the expense of buying new gears. & a new modified trac-loc carrier, really gets the price up there, & one still hasn't factored in cost of small parts & labor, or whether the axles are bad (chewed up under sealed axle bearings). IF no external seals on the axles, the axles are sealed bearing style, & axle bearings need to be removed & axles ck'ed for wear. Installing new posi, gears, & axles, one can easily put $1350 into a 28 spline type "O" rear, & when done, one won't have the overall strength of a fresh built $900 8.5 A-body posi rear, as the 8.5 housing has more pinion support. Hope this helps. Got Posi? :3gears: Roger
If you need it,I have a 12 bolt Olds posy carrier that had 323 in it.If you are interested,let me know.BrunoD.
Beanbagger: Not sure where you're located, but if you need an Olds rearend re-worked, Brian Trick is the guy to see. He redid the original 3.08 open from my '67 442 with a new posi carrier, 3.91 gears, seals & bearings, blasted & painted for less than it would have cost me to buy the parts. Nice guy, too. Brian's in Erie PA. e-mail him at thetrickfamily@yahoo.com
