The bed, and it seems the entire right side of the vehicle sits a bit higher than the left. I notice this on other older model trucks. What is the reason?

Could be worn or broken struts. That would be the first thing I would check.

it would actually be worn out leaf springs or warped leaf springs or warped brackets......you do not have struts on the rearend or a vehicle

It's the good old chevy lean... It just happens. Most folks doing a 4/6 drop tend to adjust the rear shackle length to level it. ITs really noticeable on lowered trucks.

my truck does the same thing new suspension all the way around cept for the leafs its just how it is

bent or worn body mount

worn/bent springs or stabilizers. my 89 riviera leans the same way too. most peeps make faster right turns so naturally the right side will be raised. for show time u could try putting the vehicle on a slightly inclined slope to try bending it more even. just remember not to race it on said incline; if too steep a turn, it could roll over. i've parked it lately on an incline too and the car looks more even now. nothing is really wrong its just the fast right turns.. a coworker asked the same thing. ;]