I've identified the transmission:
The guy at drivetrain.com said its manufactured by New Process/Tremec (which he says is the same company). I gave him the numbers/letters stamped on the side of the tranny and he said its RUG, SMOD (it has a shifter turret mounted on the extension housing). The numbers/letters on the tranny are:

RF-D9BR-7006-AB
ACE/CO 2
C-2604194

There are also numbers/letters stamped on the portion of the rear extension housing of the shifter, they are:

RF-EOTR-7F306-AB
C-2604302
FA1

A rebuilt replacement from drivetrain.com is one thousand, after you return your core to them.

I'm also considering installing a rebuilt toploader 4-speed, which would be fifteen hundered from David Kee Toploader Transmissions (can't get a core refund).

A third option would be finding a used toploader, but I want to find one that would be a bolt-in replacement, without modifying the driveline, or anything else.

Can anyone offer any suggestions on strategies for finding the right-sized toploader transmission?

 

Ones that came out of rachero/fairlanes are a bolt in replacement, but then again they are all about the same lenght, its just there's tailhousing that put the shifter in different locations, so you need to get a flat center piece (that removable pieceof the floorpan) If you check out my gallery out you can see about where one of a rachero/fairlane puts the shifter at: https://www.ford-trucks.com/user_gal...7&albumid=4022.

But i didn't any problem with the mounts or the driershaft lenght at all (both tranny use a slip yoke and not a steady bearing type d-shaft) but the toploader is an inch or two longer but its not enough to make a difference. But just to make sure they are going to be about the same lenght (as i'm not 100% sure on the tailhousing lenght) measure the length of you tranny and compare it to the toploader if you decide to get a toploader.

The one thing you will have to do (if want the shifter to be in a comfortable spot, as the shifter handle that comes with them are not) is make a shifter handle, its not hard and only took me abouta half hour for the one you see in my gallery (i've since junked that one as i now have a new hurst shifter), i had to weld the bottom wedge thing to the bottom and cut threads on the other end for a t-handle.