Rear end housing?

[Turbo Rookie]

I got my hands on this rear end (looks like an 8.5 - 10 bolt) and was wondering if it's for a grand national. There is some rust...see pics. Was wondering if this is okay and how much should it go for? Thanks!

 

[Red Regal T]

Looks like an 8.5. Rust looks minimal and non-problematic. The outer groove is where the seal seats.