Anybody have much experience with these? I'm retoring a '66 Chevelle (I'm not going for a factory original restore, so maybe call it refurbishing). The stock rear was a 3.08 10-bolt. I bought a 4.11 positrac 10 bolt rear, and the seller claims it came out of a late 70's Oldsmobile. What I'd love to find out is - are all 10-bolt car rear ends similar enough that I could transplant the 4.11 gears & posi unit from the one I bought into my car's original 10 bolt housing?

My thinking is - this way I wouldn't have to do any welding on the axle housings to get my trailing arm/shock/spring mounts where they need to be, and I'd have a stock width unit & not need to use offset wheels. Do a little work to avoid a little work I suppose.  

There are a couple different 10 bolts gm made throughout the 60s and 70s . The original from your  chevelle should be a 8.2 chevy style 10 bolt identified by the rear cover. It should have a half circle that kinda bubbles out on the drivers side of the pan and 10 bolts that hold the cover on. There is another buick,olds,pontiac 10 bolt also an 8.2. The pan on this one has a half circle cut out on each side even with the axle tubes. These two are not interchangable.  

You could also have an 8.5 or a 7.5 10bolt lets figure out what you got before you go cutting and welding the brackets.  

I have a 75 Omega with a 10 bolt in it.  On another site I looked at it showed some visual differences between the 8.2 and the 8.5.  The 8.5 has a squared off bottom on the casting, and the 8.2 is rounded.  The cover on mine has the bulge on the driver's side with a slightly smaller bulge right next to it on the inside or toward the center of the cover.  I have no idea if it's posi or not; the motor is not strong enough to spin the tires.    I bought it a couple weeks ago for $500 bux.  It runs and drives, but doesn't have the balls to even spin the tires in the dirt, it just goes.  I put a carb kit on the dualjet carb, 2 barrel... it's a 260 V-8 original motor, 102k miles.  It sounds like it's firing on all cylinders, but it seems like it's timing is retarded or something.  Have to roll it a few times to fire up.  Rolls over real nice, and idles fine in and out of gear, but no balls, whatsoever.  Anyway, I started wondering if I got a posi rear end.  Any other way to tell posi from non posi?