So, Im in the process of buying a 1996 Ram Stepside.

I was wondering what the dimensions of the box are roughly (Width, Length), and any other information on the pickup.

 

Since your truck is 1993 or newer, you should be asking your question here -> https://dodgeforum.com/forum/2nd-gen-ram-tech-64/

But since I have a strange fetish for those stepsides, I'll try to answer your question.
Either it is a chevy bed with dodge taillights, and would follow 88-98 chevy dimensions, or it is either a one-off or custom aftermarket bed. Dodge never made a stepside on 94-01 rams, but every once in a while, I run into one, and they all seem to have a slightly different bed.