Transmission question for Garden Tractor

I have an older Garden Tractor (917.251572) that is having trouble with the Hydro Static Transmission. I've been looking for a replacement (used), but haven't found anything local (NE Florida) so far. I was just given another old Craftsman Mower today that is a little smaller (42" vs. 50") but the transmission is supposed to be good (haven't got it started yet). My question is whether it is reasonably possible that I can take the transmission out of this unit (Model number 917.270822) and put it in my Tractor? If I have to do a bunch of modification to make it work, I will just keep looking, but I thought I'd ask. Any help would be greatly appreciated!