12 Bolt ID Code

[ZiggyL78]

I just picked up a 12 bolt rear.Passenger tube says CDK0302B1.Passenger casting B180.Drivers casting 87890.There is also a casting # 00N20.It measures 62" outside drum to drum.Maybe 62 1/2".It's in my truck and raining right now.
From my research it's a 1970 A body with a 2:56 posi built in Buffalo NY.I was told it was out of a Monte Carlo.I can't see a posi tag.It's quite clean for original.Is it normal to have orange paint on the shock mounts?One brake drum is seized.What do you guys think it's worth?
Thanks