I have a mid 50's 3 speed small mounting bolt pattern transmission which should be typical of the '59 Y-block bell housing you mentioned. It is a passenger car bellhousing, right? The outside diameter of the bearing retainer on my trans is 4 47/64" so I think it would be safe to assume the bellhousing bore would be 4 3/4".  I have many questions about your project but anyways, good luck and hope this helps....................

64F100 57FAIRLANE500

if the transmission is out of a small block the imput shaft will be 1/2 inch longer.you need to grind 3/8 off.all 4 bolt holes line up.you will need to turn down front bearing retainer.

I’ve been following this over on the HAMB. If I’m reading it right, you’ll need to turn the front bearing retainer about 1/4”. Based on what I did some years ago with the later Ford 4 speed o/d discussed there. A measurement from Ford Dearborn will tell you.

2 of the transmissions to bellhousing bolts will line up. You may have to drill and tap the other 2, it’s not a big deal. The input shaft length I can’t remember. May need a 1/8 or 1/4 inch shortening. That is also not a big deal, I’ve done that on T-5’s. Watch the length of the clutch splines, but that should also not be a problem.

Using the Jeep shifter on the top cover, I don’t have a clue, but it would probably be appropriate for a model A.

Anyone interested in this discussion, here’s the link.

https://www.jalopyjournal.com/forum/threads/gear-vendors-with-a-3-speed-toploader-anyone-have-it.1279511/



miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

I'm not sure exactly what you are swapping but if you are planning to use the trans pictured, the input shaft looks a lot longer and different than that of a Ford trans. As far as the outside diameter of the bearing retainer, I will be able to take a measurement for you tomorrow, if you still need to know. 

64F100 57FAIRLANE500

Does anyone know what the diameter of the big hole that supports the bearing retainer is on what's PROBABLY from a 1959 Fairlane? 
I've got a 3 speed toploader in my Model A coupe behind a '59 292 and it's all working...I have another transmission with OD (AMC Gremlin T-150 with Laycock de Normanville OD) that I want to stick in there but would like to figure out if that bearing retainer is the right diameter as is or if it'll need to be turned down (while it's with the transmission guy) without taking it all apart in case I want to go out for a blast in it.