shorten frame from longbed to shortbed??

[crosby]

has anybody done this? If so, where do you cut, and how much? I would guess you'd have to take some out of the center before the front rear spring hangers, and some off the tail end too. I have a 3/4 ton frame in decent shape, and want to build a stepside (4x4). If I can use the 3/4 ton frame, that should be stronger too. My stepside frame has rotted out rear spring hangers, and it's not all apart yet either (the truck). Any suggestions? Thank you guys!!