Show some pics of the input shaft and casting number of the tail housing.
It's an a-body trans. If that is what you were looking for you got it.
You can open it up and count the markings on the gears to verify the ratios being wide (2.66 1st) or close (2.44 1st).
ID Guide is on the Brewer trans website.
Issue would be from the inside gears Being rusty or engaging teeth being toasted. Did you open it up and inspect? Did the seller say the insides looked good?
