So I'm the new proud owner of a Mesa D-180 head (thanks Kurt!) and figured I might as well drop it into the 4-space SKB rack I've got lying around. But it looks like Mesa...uses some kind of non-standard rack hole spacing? The holes on the head line up exactly between the ones on the rack, and there's not even close to enough wiggle room to get them in line. This seems really weird (this is an SKB case, not a weirdo off-brand or homemade one)...am I overlooking something obvious?