I just got an 80 k5 that has the 73 front clip including the cab removed. Since I have gotten this truck it has come to my attention that the 73-75 had a tq box if not the right name extra bracing under the cab. This truck does not have this. Do I need to add something to it, or since it's a full-frame

truck will that be enough, and could someone give me pics of what the factory ones looked like?

 

Torsion boxes, torque boxes, rocker boxes, etc. are all names for these things. The reason for them is to increase the structural rigidity of the body in the absence of the roof over that gap. Given the purpose of these boxes, they are attached with a LOT of spot welds and are quite difficult to remove. As such, I'm betting that if the factory torsion boxes are not there that it is an '80 body converted to a full convertible style. Here is a link to a write-up on CK5.com on the Full Convertible Conversion for more info. A picture of the floor area under & behind the front seats would tell that story as the floor profile changed for the 1978 (I think) model year by extending the floor under the front seats back further to add a footwell for the rear seat passengers. I also believe that the rear seat changed at that time to be a hinged seat that pivots on the front mount and latches on the rear mount so the seat can flip up giving more bed space in the back. I'll be adding this feature to my '74 when I get around to replacing the rear floor.

As far as the need for the torsion boxes, in general most that convert a later body over to full convertible do not do any additional work to reinforce this area. I have seen where some that do offroad their trucks fabricate a rock slider that is welded in place of the rocker that serves as body protection along with added rigidity to the body -- One example --> This is how I made my rock sliders on CK5.com.

 

Thanks for the replay, whoever did the conversion did try to compensate some. there is a 6 inch gusset at the back of the door on the floor. I did run across a company that does these conversions and the replaced the inner rocker with a 2 by 3 tubing.