3600 is the 3/4 ton series, which encompasses all models; e.g. pickup box, stakebed, suburban, canopy, etc. All 3/4 ton trucks are 3600s. 3604 is a 3/4 ton truck with a pickup box. If you had a platform bed it would be a 3608. I have most of the model numbers on my web page . Click on the Advance Design Trucks menu and then choose Models.

HTH

Jeff Nelson

"Beer is proof that God loves us and wants us to be happy." - Benjamin Franklin
"Always do right. This will gratify some people and astonish the rest." - Mark Twain