Flushed the 2008's frame rails with the truck on jackstands, wheels off (getting it ready for a lift). The rails were packed, I say PACKED, with dirt. I bought it a month ago, Carfax showed it was a Western Colorado truck all of its life.
Not much gravel, fine grayish sand/dust. The rear outside bumpstops there's a hole in the mount that accesses the interior of the frame rail, the sand was literally overflowing out of those holes.
The good news is there are no rust holes in the frame, I did a thorough check for rust before I bought it. Typical surface rust. I used the garden hose with a spray nozzle and put pressure into each and every access hole I could find on the rails from front to rear.
There's access holes all along the frame rails from front to rear, every one I could get my pinky into was filled with that sandy, silty material. It took about three hours to get it all flushed out, it was packed in there hard.
I'll flush it some more tomorrow, and after the XREAS is removed and the suspension is disassembled I'll clean up the surface rust and give it a good bath of Fluid film before it comes off of the jackstands.