"O" Type rear axle

[scrappie]

Can anyone tell me what an "o" type axle is ? Does the O stand for oldsmobile or the shape of the carrier? I also have a rear end that was supposedly pulled from a vista cruiser that is a posi unit. Would this be considered a turnpike cruiser? I can't find a code because the thing is so rusted. What were the gear options that would more than likely be in that car? 2:78, 3:08? The rear cover has a rib that protrudes in the top right corner and also has 10 bolts. Does this sound like an Olds rear end? How do I identify?

[2blu442]

I've seen diagrams that show the difference between the rear ends used, but can't remember where I saw it. I pulled a posi rear end out from under a 1970 Vista Cruiser years ago. The car had a 455 4bbl TH400 and the rear end gears were 2.56. The housing on Vista Cruisers have different shock mounts so I don't believe they will fit in a Cutlass/442 but the guts from the rear end might interchange, but I don't know for sure. I would expect the gear ratio to be 3.08 or taller. Depending on what year the rear end is out of it may have 31 or 28 spline axles, that's something else you can check. If it is the 31 spline then those axles would be in more demand than 28's. John

[Oldsguy]

"O" stands for Oldsmobile to differentiate from the corporate GM 12 bolt. They were only made in a 12 bolt variety so the 10 bolt you have is not a type "O".

[joe_padavano]

The Type O axle was used on 67-70 Cutlii. It has a twelve bolt cover but only TEN BOLTS on the ring gear. It is NOT a 12-bolt GM/Chevy axle and none of those parts can be used. The Chevy 12 bolt uses an 8.875" ring gear that is held on with 12 bolts. The Type O uses an 8.5 inch ring gear held on with ten bolts (just like a GM 10-bolt axle). The one big advantage of the Type O (and other Olds 10-bolt axles used in 71-up) is that the axle shafts are retained at the outboard end with pressed-on bearings instead of the C-clips used on Chevy axles.