My experience with mucie's is that they are all old now, and the aluminum case expands making them much weaker than when they were new. I had a saginaw in my '67 and did blow it up with my stock 275/327. But I was a stupid kid at the time
I had to have a muncie after that because everybody told my how much better they were. I probably blew up atleast 6 of them in a few years. I did find that the 1 inch countershaft mucie's did live longer. And also, the muncie's don't shift well in higher RPM's.
I agree with hotrod on a T-10 if he just has to bang gears and blow up parts
I am planing on finding a correct date coded saginaw to put back into my '67, and just drive it a little bit smarter.
So if your Saginaw has a date code of "R7C20" I am intrested in buying it.