there is no significant difference in the 3800 and 4100 frame
I guess I should have looked it up before writing that. Without looking it up, I think the difference between a 3800 and 4100 frame is actually the extensions used to mount the big truck bumper instead of the little truck type.
I did look up the frame dimensions looking at the height, width and thinkness of the main rails. 3800 and 4100 are the same. 4400 and bigger Chevy trucks including 5000 and 6000 series are all the same according to my '55 1st resto pack.
