[rotorwrench]

I personally would want to look at the planetary gears and the condition of the sliding sun gear. I'd also make sure balk ring is still a snug fit and there is little or no wear in the sliding track of the pawl.

With a regular transmission, a person can get away with flushing and running it but on an old R10 overdrive, I'd want to make sure nothing is bad back there. If you've ever had one lock up while cruising along at 70 MPH, you will understand why I feel that way. It's a lot easier to do now than later. If it's good then all it will cost is the gaskets, a rubber band, and maybe a seal or two.

The Ford Service Manual should have info in the accessories section. I have the Lincoln Mercury Overhaul Manual so that works for me. Mac's book will help in the front section some but if it's a 51 then it may have the late diamond cut gears that are different from the early Ford stuff.