That wasn't the intent of our responses at all (you being a "bonehead"). Sorry if it came across that way. It was more in the sense that it is surprising, as these are straight forward, easy to install, great quality, and I have never of them not fitting properly (doesn't mean it hasn't happened though). Either you got a couple of bad ones, your truck bed could be little off, or something else of an exception is at play here.
I guess to answer your question directly, no I do not know who makes them for GM but if you are looking for good alternatives that are less expensive, as you elude to, then I would recommend a Truxedo, based on personal experience and what I have heard about them from other members.