The old frames were designed to twist. We all see those guys on TV boxing their frames. Usually it's a hot rod, purpose built frame. This should not be done on our AD or TF's as Jerry said. These trucks had big old heavy motors. Most of the time heavier than the V8's you put in them later. So the frame can take it. They also had a 4X4 kit added to them sometimes. Those guys on TV go nuts with that boxing crap....and you can do harm to the metallurgy and the original design intent by welding and not knowing what you are doing. If you are going to build dragster HP, get an aftermarket frame. If you go beyond 70MPH you will need brake, steering, suspension upgrades up the yin yang. (I really think 60MPH but everybody here would balk at that)

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn