"I'm looking into a Saginaw 4-Speed to replace my original 3-Speed in my '72 C-10."

Bill, there is a very long established manual transmission parts and rebuilding facility in Los Angeles called Al Silk Gear Company. I was in there once on another matter and they showed me something about the Saginaw 4-speed that you might want to consider. The Saginaw 3-speed was converted to a 4-speed by making all of the gears very narrow and keeping all 4 forward gears and reverse in the main case that is the same size as the 3-speed case. Narrowing the gears reduced their load carrying ability.

In contrast, the Muncie has wide forward gears in the main case and reverse is in the tailhousing.

I have a '78 El Camino with a factory 350 cid engine and Saginaw 4-speed and there have been no transmission problems because I drive it like the old man that I am (66 years). The only maintenance I've had to do on it is fix oil leaks by replacing the tailhousing bushing and oil seal, the front seal and the shift shaft O-rings.

Ray