It appears that I have a mutt for a diff, so what would one pay for a nicely redone 69 date code 12 bolt pos , non # rearend ?
Honestly if it's a posi with a gear ratio that will work for you, I wouldn't worry about it. If it is functionally good for your needs, don't worry about the "numbers" at this point.
It is possible that it's a modified 1970 Impala rear, but without the casting date I don't think we can say for sure.
Price for a replacement will depend on what you want, but the engine and trans aren't original either - correct?
Engine is not for certain , and at this point probably not trans either . So I do agree why bother , but we just love to tinker with these things , so I'm always looking for something to improve .
Well my engine and transmission are not original to the car either. Engine is a 1974 454 from a truck. Bottom end is over built, to hopefully last forever. 4 bolt main block with forged crank, forged pistons and good aftermarket rods, cam is close to LS6 specs. Transmission is a 1968 M21, but from a Chevelle. Rear axle housing is original to the car, but none of the "guts" are (different posi, gears, aftermarket axles).
So, you are not alone. Many cars don't have the original drive train, for whatever reason. The main thing is to enjoy these cars and enjoy life. I love the "numbers" but when it gets right down to it, that doesn't make the car drive any better.