Some people who aren't really into this vintage say the 3100 is the short bed and the 3600 is the long bed. Although it may be true, it has more to do with tonnage.
The truth for ME is, when I want to pull 3 or 4 inch diameter trees out of the ground, I chain them up to my 3600 and they just come right out. But I don't even THINK about doing that with my 3100's.
The 1/2 ton (3100) is by far the most popular and desireable when it comes to marketability. When it comes to practical, more versatile, stronger, and more useful, the 3600 wins hands down.
I sold my 3600 because I ran out of trees to pull, and needed the smaller footprint of the 3100 for the garage, parade duty, desirability, and lighter makes the truck peppier, more maneuverable, and more fuel efficient. But that's just me.
On the other hand, someone is trying to sell me a barn find, very clean 3600 and I am really really thinking about it. LOL!
