Pre war GMC trucks - 39, 40, and ?

Feel free to post pics.

Looking at building a shop truck and I think I am in love after seeing a pic of a 1940 GMC 2 1/2 ton commercial truck. Anyone know what years they made that body? Looks like the 39 and 40 are about the same. Any other years???

I know nothing about early trucks...

 

Here is a '39 and a '40. Both I drove and both while sure footed were pokey old things.
Normbc9