hey, I just bought a set of used headers for a BBC....but when I tried bolting them up...they won't go on, because the flange hits the bottom head bolts! I don't know what brand the headers are, and neither did the guy I bought them from...but they have a pretty think flange, I think. I saw pictures of them mounted on the truck before they were taken off, so I know they should fit. as far as I know...everything should be the same for all big blocks, right? I mean...it wouldn't make a difference what heads they are? they're 781 heads, in case that does matter. anyone else ever had this problem, with any headers? is there something I'm doing wrong, or something stupid and obvious I'm overlooking? any help would be greatly appreciated, thanks.