GM C channel frame -> Boxed frame

[jetman]

Seriously thinking about buying a newer model GM 3/4 or 1 ton LWB standard cab 4x4 and cutting down to accept SWB bed.
Would like to stay w/ C channel frame for ease of fabrication.

Does anyone know the model year GM went to fully boxed frames for these pickups?

 

[Craig 85]

They just shortened a 2003 Duramax on Truck Tech. Here's the link to the show.

https://www.powernationtv.com/episode/TT2017-04/supermax-shrink

 

[1987 GMC Jimmy]

Yeah, it looks like they switched to a boxed frame for the GMT900. The newest you could go is 2006 with the exception of the 2007 Silverado/Sierra "Classic" trucks where they retained the OBS concurrently for a model year alongside the NBS.