This part came from an Oldsmobile dealership in Eveleth, Minnesota, which shut down in the 1970s. This part was stored in the back of the dealership where there was a leak in the ceiling. That is possibly  the reason there is rust on the outside and not on the inside of the muffler. Please take a look at all of the pictures. The reason I listed it so cheap is because do not know for 100% if it is NOS.

Feel Free to message any questions about this part.