1. what is the major differance between a 1950 chevy and a gmc besides the grill?
The motor and the front crossmenber and of course anything with a logo on it. Because the parking lights are located different the fenders are different but not hard to interchange.
2. how interchangeable are the two?
What is your goal? A running truck or a restoration?
3. And I also should ask how interchangeable are the years between 47 and 53?
There are a lot of small differences between the first Advance Design/New Design trucks and a '53. Major differences between '53 and a '54. Many of them can be adapted one way or another. Again, if you are restoring the differences matter, if not you can do most anything.
4. I know the 3100 is a half ton but what is the 1 ton and how interchangeable are they? is the body the same or just a look alike?
A 1-ton is a 3800 and someone else has already described the differences in sheet metal and bumper.
A GMC 1/2-ton is a 100, a 3/4-ton is a 150 and a 1-ton is a 250.
5. last one. can I put a half ton running gear on a 1 ton body & frame?
Front would be relatively easy, but the rear would be more complicated because the frame width and suspension are different.
Hope this helps. I own both 1/2-ton and 1-ton trucks if you ask specific questions I may be able to give you pictures and measurements. However I'm away from most weeks so I may be slow to respond. Especially if I forget or its raining...,
