I have two questions, I see the term "SM420" transmission used a lot here. What is it? There are charts and silowets of the later three, four and five speed transmissions abut these arn't mentioned. Are they GM, Muncie, etc., and do all the 3/4 and bigger AD trucks use this tranmission? I have the original four speed in my 3/4 ton 1950 but never knew what it was called.
The other thing was the dipper engines. I think it is a testament to this engine that there are so many still running 60 or 70 and more years after they were built. Most of them were worked to death on farms and hauling commercialy. Of course if your going to try driving them on the freeway at 75mph everyday or hot rodding them to compete at the drag strip then they certainly won't hold up. So whats REALLY wrong with the early inliners???
Denny Graham
Sandwich, IL
