notanewbie,
that would work on older trucks but with the newer trucks they use multiplex wiring or optics to control electronic valve banks to dump air, activate abs, interaxle lock, etc. You need the wiring harness extension to make it work. Plus it is sealed meaning a problem free solution in the future.
Shadow,
I got that quote from Central Wisconsin Body and Hoist in Weston WI (Now called Equipment Lift?), Northern Repair and Welding in Ringle WI also does an excellent job. That did not include the frame. I had enough frame, just had to move axles back 4 feet. They did quote me in the past for other projects that needed frame and they charge the cost of the steel and the bends. In this situation if I were to add frame it would cost an additional $400. But the $2800 quote did include the building another driveshaft 4' long and balanced with carrier bearings, wiring harness, air lines. Basically drop off and come back two weeks later and drive away. Everything complete.
That is a good price but the shop was 1 month behind and I didnt have a month to wait so I did it myself. I did end up sleeving the entire frame up to the back of the steer axle spring hangers. Just wanted the double frame for peice of mind and I had $900 in the steel (1/4" grade 50 frame stock bent to dimension from flat steel).