'67 mustang coupe auto trans

That looks like a smallblock C6 . . . that transmission was never installed in '67 Mustangs from the factory (the only C6 transmissions in '67 Mustangs were behind big block engines, like the 390), so someone has installed it.

If it needs to be rebuilt, it likely wouldn't be worth more than around a hundred bucks or so, because you can find rebuildable ones just about everywhere for around that price that are in vans and pickups, as well as once in a while in 71-74 Torinos & Rancheros behind 351's (usually 4V engines), and 71-73 Mustangs (also behind 351C 4V engines). I'm sure there are lots of other applications where you can find a smallblock C6, but those are some of the most common.

Good Luck man!