As I remember, I had a choice between 4000 and 4500LB. when I was getting parts for my D350. I think I went with the Heaver of the two choices... I will check my truck's data plate tomorow to see what it says. What parts are you looking for?
I guess what I am thinking is that the parts store can break down application's by GVRW, my truck is a chassis cab, with a 10,100 GVRW
Wait, I am Just a little tired, and thus slower than my normal 'slow' state. . My service manual states that the D350's that came with Dual's were body styles 63, and 64 having a GVRW of 10,100 and 10,500LBS. the D 350 with a body style of 62 does not have duals, and has a GVRW of 8,700... the more I type the less certian I get, as I was under the assumption that Dodge did not make a single rear wheeled W-350 or D-350 back in the 'first generation' time for me to go to give up for tonight.
Jason