Hey,
welcome, I'll chime in and others I'm sure will add to what I know.
The grill, Engine, tailgate, and interior stuff Steering wheel, gauges and anything else that might have gmc on it are different.
I'm not sure if the front fenders are the same or not I am pretty sure the rest of the truck is the same.
Sheet metal is the same 1/2 3/4 and 1 ton except for running boards, splash aprons and bed sides all depends on the length of the bed.
My 3800(1 ton) has a 9 foot bed and so has the long running boards and splash aprons.
3600 (3/4 ton) has a bed longer than the 1/2 ton but shorter than the 1 ton.
49-54 are mostly the same. ONe piece windshields come in 54, and wing vents were available in 52 (I think...)
OK.. I think that covers most of it...
there is a ton of info here:
http://chevy.oldcarmanualproject.com/chevyresto/50index.htmenjoy!
Jeremy
