Re: rear diff decoded
[QUOTE=Big Dave;318551]10 bolt corporate (AAW 8.5 inch ring gear) with disc brakes were installed under a Cadillac Seville (X-body same as the Nova) from 1976-'79, and under first and second generation Camaro with the JL8 brake option (very rare option); or the second Firebird SE with the WS6 suspension option which is much more common. Neither of the second gen F-body rears will fit under a X-body as they are too wide and the spring perches have a different pigeon toed spring mounting angle. The first gen Camaro JL8 rear is worth more to a Camaro restorer than the value of your Nova, as they were normally installed on factory prepared Trans Am race cars.
Odds are it is out from under a Caddy. Bad news is those brakes only work if they are maintained: which is why they were discontinued, as every knows a Caddy owner can not be expected to do maintenance on their cars. Without constant adjustment the brakes will nor work at all, so they were involved in a lot of wrecks. And unhappy Caddy owners.
The third gen IROC Camaro were fairly common, and they had rear disc brakes. Nut that rear end was a coil spring mounted triling arm suspension with a 7.5 inch ten bot ring gear that will not fit under a Nova without a lot of work. The brakes will however bolt up to any ten bolt, so the brakes may have been swapped off of another car as opposed to being a factory install. Which brings up the point that GM used five different brake manufactures for their rear brakes. What you have can be identified by part number or casting numbers. Brakes were based upon four piston Girling, or Brembo, or the two piton PBR using a fixed bridge, or two different GM designed single piston full floating brakes.
Big Dave thanks for all the info