on e bay there is a 92 dodge with a 4 door cab off of a 86 i was just wonder if it was that easy or do you have to lenghen the frame i cant tell if it is a short bed or not i have a stand cab with long bed or is there a place to get the size of frames on inter net

 

I saw that one, it's a stretched frame to acommodate the crew cab and the long bed. Stock crew cabs were short beds.

 

The "belly" of the frame ( portion under the cab) is longer on a crew cab than other frames (std or club cab). I will crawl under mine later and give you the length.
Crew cabs came in both long and short box modles. Especialy one ton (10000 GVW) that only came long box. Mine was a 8175 GVW srw crew cab short box that I streched the frame 13" (actualy cut the back off a 8' one ton frame and welded on mine) but you coul cut the belly of th eframe and add the differance there for the crew cab.