Is it possible for an 1967 327, 275HP (powerglide) to come with a 12 bolt posi? If so, which posi unit would be right? If it has to be a 10 bolt posi unit to stay factory correct, which one(s)? Thanks

Hello 327:

This should help some: http://www.camaros.org/diffs67.shtml#FNa

I beleive that the 327/275 only got a 12 bolt when a 4 speed transmission was ordered creating the sleeper performance Camaro, LM30/M20 option. I am sure the real experts (LM30/M20 fans) will chime in, but this will get you going.

The standard axle for the L30/M35 is a 3.08 10 bolt. We do have record of a couple of 12 bolts in these cars, but that is the exception, not the rule. We also have record of quite a few 2.73 10 bolts (economy ratio). The performance ratio was a 3.55 10 bolt, but we have no record of any so far.
Hope this helps.

My 67 L30/M20 came with a 3.07 12 bolt posi.

My 67 L30/M35 came with a 2.73 10 bolt open.

Mine also has the 3.07 12 bolt posi.

Mine has a 3.07 12 bolt open.