Truck is a '90 CCLB 4x4, bed has been replaced with a flatbed before I got the truck. Bed was definitely not done "right" with spring loaded clamps on the frame that I see on modern commercially installed flatbeds, and instead just u-bolted to the frame with some steel tube and plate spacers to accommodate the over axle rise, in a very backyard redneck engineered way, lol. I live out in a rural area on dirt roads, with the usual bumps, dips, holes, etc of "out there" roads. Driving down the road, looking through the windshield mirror, I can see the headache rack moving back and forth what looks like 5-6 inches in both directions. It's a smooth movement, not jerking around like it's loose on the frame. Headache rack is welded to the flatbed too, so it's not moving on it's own. I have a headache rack bolted to the pickup box on my '96 Chevy K2500 too, and have never seen it moving around like this on the same roads, but the Chevy obviously isn't built anything like the Ford is either, lol. I know long wheelbase trucks will have some frame flex, and you don't want extreme rigidity in the frame, but I'm not sure how much is too much, or if this is normal with having the flatbed directly clamped to the frame? I ask because this truck has been parked for about 9 months now, and now my other daily truck is having major issues, so I'm considering selling that one and putting the Ford back on the road. But I don't want to dump a ton of time and money into this truck only to find out I have major frame issues or something else like that afterwards, lol. I don't recall ever having felt/seen other indicators of a broken frame, and have had 10K+ pounds on the trailer hitch many times. I'm planning on pulling the flatbed off soon to do some work on the fuel tanks, due to a tire blowout taking out the fuel filler on the rear tank, and some other issues back there too, so I will have a chance to take a better look at the frame overall.