I'm thinking about stretching one of my 1 ton C&C frames to mount a dry van box and I'm looking for the OEM frame stretching and modifying manuals and/or procedures that would have been available to upfitters when these trucks were new.
The truck in question is a 1989 GMC R3500 C&C although I do plan to swap the cab, motor, ect to my 1986 K30 C&C chassis to save the 4x4 conversion.