[ijames]

Yes, the two more subtle downsides to moving a toolbox to the rear that I thought of (beyond limiting cargo access) was the increased polar moment and the fact that everything in the box is probably going to get shaken up a bit more. I'm still curious if anyone with the instrumentation and a box would be willing to do the test.

I bought the wood and it's all cut up, to make a 44% cover for my 2005 GMC 2500HD extended cab short bed (77" bed, 36" cover minus about 2" of overlap with the tailgate top). Barring rain I should get it on in a couple of days. I log all fuel so I'll know in a couple of tanks even with my local mix of driving, without having to wait for another highway trip, what the gain is. From your Cd list I think my truck should be in the .45ish or slightly better range as is, so my gain won't be as good as that C10. Oh, someone had mentioned that the S10 beds are slightly tapered these days, I found out mine is too. It is about 3" narrower at the gate compared to the front.