So apologies to b-dog for highjacking this thread. I have an '02 Silverado dually long bed and am looking at in-bed auxiliary tanks. Pretty much had decided on the RDS 51 gal. fuel/toolbox, or the 60 gal. fuel/toolbox combo. Both are 19" tall according to specs. I measure 19-1/2" to top of side rails. Really want the toolbox option. Have been looking at hard tonneau covers but am undecided as the fuel tank needs to sit 1-1/2" from front bed rail to allow toolbox to open, and don't seem to see any covers that will work and still allow opening of toolbox. Also have fiver hitch in bed. Anybody have recommendations? Thx.