I'm right there with oldcarandtrucknut. I have ordered plenty of parts and can't say I'm overly thrilled with most of the vendors. The parts are junk but I need to use something until I find old parts or can afford to have my parts refabbed and/or rechromed. So, I'll throw the chinese junk on there for now.
I have based most of my recent purchases on customer service, and Jim Carter, LMC, and Obsolete Chevy win out every time on that. Obs Chev actually calls me to verify a part when it doesn't match my listed truck. That has saved me more than a few returns. On the flip side, ChevyDuty doesn't seem to care. If you mis-ordered or double-ordered, tough. If the part doesn't fit like it's supposed to, tough. The answer I got from them is "we've used those parts on our trucks and they fit fine." (click) So the only time I order from ChevyDuty is when NO ONE else has the parts.