Hi, I have a 92 Mark III. I hate those bed rails and stuff too.
Mine came off pretty easy. If yours are like mine, they are held in the stake pockets with a nut, a long screw and flat plate nut on the bottom of a block of rubber.
turning the nut, shortens the screw and makes the rubber block bulge and expand holding the rail in place. Loosen the nut, but don't remove it. The flat plate will fall off the bottom of the block(lessens resale value). Anyway, after loosening the nut, pull straight up on the bed rail. It might be a tough pull, so you might have to wiggle and pull a bit. It should pop out of the stake hole. Hope my directions were clear. Good Luck!!

 

I think i found the problem. I have a Roll N Lock bed cover which is in the way of the bolt. I dont think i can get the bed cover rails off enough to get at the bed rail mounts. Looks like I may have to live with them.

 

I loosened the bed cover rails but cant find any nut holding the rail on.

 

I have a 95 R/C Flareside Mark III with Mark III beadliner and body color rails. I want to remove mine too. When you find out how, post pictures please. I would like to see what you came up with.

 

You have to look up from under the truck, the fenders are hollow and you can see the bolts all the way at the top

 

I looked up through the bottom and found the bolt, but there seems to be only a flat washer and no nut to turn. Am i missing something here?

 

Ok, apparently only the rear drivers side bolt doesn't have a nut on it.