that is a nice tranny, I have used them before.
I would like to recommend before you purchase that transmission, remove the side cover (7 bolt)and inspect it. If it have heavy wear inside may indicate hard use, most important of all WATER damage, if you see water damage(rust from sitting outside or stored in basement and had a flood), most likely the parts in the overdrive unit will have pitted or corroded and are hard to find replacements some parts are interchangeable with the older units, the gears inside of the transmission itself are interchangeable with other Saginaw trans as long as you have right ratios.
I have seen trans in my past with water damage and usually most parts are ruined,
good luck with your find.
