57 Tbird tail shaft ID

[Blown Gasket]

I bought a 1957 Thunderbird two years ago and I am thinking about putting a new seal in the output end of the 3 speed standard tail shaft. Over the years the engine and drive line have been bastardized. The engine may be out of a Y block pickup truck, at least the oil pan is, power steering and brakes were added with disc in front and the auto trans was replaced with a three speed standard shift. There are many other changes so it is hard to tell what they are for replacement parts. I have most under control except for the transmission. I can see the tail housing casting is different than the standard Tbird housing. I know there are several seal sizes both OD and ID and I would be guessing at the right one. I jacked up one side of the car today and tried to get casting numbers off of all the transmission parts and I got some. I'm old and can't move around under cars much but I'll be putting the car up on ramps in a few weeks to hopefully measure the tail shaft. Here is what I have gotten so far. Side cover on the trans, (AB 7222-b) and that may be from a BW 259 Three-Speed. The tail shaft looks like (WAR 7651-a) the W may be a T but it's hard to tell. I found a post online what the poster said he pulled the trans out of a 1962 Mercury Monterey 4-door Sedan and it had the same side cover and tail shaft number but the trans number was different. The only number I can see on the trans is (9M17). I would appreciate any help.