I’ve noticed & measured the bed of my truck & the left side sits higher than the right. I bought it from out of state so I don’t really know the history of the truck, but what could be causing this? I have a 97 Chevy C1500. attached picture below. if you look closely at the cab, you can see the right side of the bed is lower. It doesn’t look like much, but def more noticeable in person.

 

Well first of all be sure it's parked on a flat surface.

Most of the time it's worn-out suspension, it can give the impression that the bed is leaning but sometimes it's the cab that is leaning so be sure to check that.

Other reasons could be worn-out parts between bed and frame, accident damage, extreme overloading or wrong loading.

 

Have you by any chance actually crawled under the truck and looked at the bed to frame mounts and bolts? Bring a tape measure while you make the trip under the truck. Measure from the top of the leaf spring pack to the frame on each side and compare. As Maikelo says one of the spring packs might be sagging. The bed mounts might be rusted or crushed from something really heavy being dropped in the bed. The frame may be bent from an accident.

 

I haven’t gotten under it and looked, wasn’t sure what to really look for at the time. Thanks