This a question for someone who has built one of these trucks. I am setting up the suspension and have the frame mounted on two engine stands as a frame rotisserie. The frame has a good bit of twist in the long direction. By locking the front so it can't rotate I can rotate the rear and remove the twist or at least most of it indicating that the frame is quite flexible. I want to get the twist out. The crossmembers are solidly fastened and I cannot detect any slippage at the factory rivets. I am going to at least partially box the frame rails to at least past the transmission crossmember. If I twist the frame straight and hold it in that condition as I add the boxing plates do you think it will stay straight? I am ***uming that boxing the frame rails will stiffen them and prevent the flexing. I have never done this before so I need advice from someone who has. Thank you. I should add that when I had the frame upright and sitting on the rear suspension and jack stands at the very front it did not have much if any twist checked with a level at the rear and at the front crossmember. The front frame arms are not perfect due to a wreck many years ago before I go the truck but it appears to have been straightened by a frame shop; i.e., they did a good job.
Not an expert, but I think you would be better to build a table that can hold the frame straight while you weld it.
Any frame needs to be straight before you go welding on it. Just holding a twisted frame in position would be a **** shoot. I wouldn't waste my time until it stayed straight without any pressure on it. Then, when the thing is straight, clamp/bracket/weld it down to a very strong steel table or jig to hold it straight and true when the boxing plates or other crossmembers are added.
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