Do you have a bumper or two, and are they and their mounting brackets tight?
Have you tried moving or pulling on every part of your truck you can get a hand on to see if it is loose.

Do you have any broken things, like a crosmember, or something missing some rivets?

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-