If we're talking aviation, a #8 countersunk screw is a #21 hole, 8-32 threads, it requires a #21 countersink. If this is what you're talking about try the yard store out of wichita kansas, they have all the sheetmetal tools you would ever need and if they don't brown tools will.
I believe my dad has the same box (drawers on the front, the LH side and a cabnient on the back?) and just had his dealer warranty the casters and drawer slides. I guess what I'm saying is see if your local dealer will warranty it if you haven't already (thats assuming that the parts are there...
I'm wanting to shadow my work box, I've seen foam that you can lay your tools on and heat leaving a depression of the tool. The only problem is I can't find it online, any help would be appreciated.