So I'm digging this thread back up to report something interesting. Or at least I thought it was mildly interesting. I've been running what I thought were the OEM wiper blades for years now, but it turns out they were the ACDelco "Professional" series. Should have known better than to trust the parts lookup on ACDelco's website.
Anyway, I looked up the real part number on Wholesale GM Parts and this is what I came up with. Part number 93441742 is the legit OEM 18" ACDelco wiper blade. They're around $12-$14 each depending on where you order them from. They come in a vacuum sealed bag that is a pain to open. They look way more solid than the "Professional" series blades, these are solid blades whereas the Pros have little cutouts on the body. Also the rubber on these OEM units is much softer to the touch than what's on the Pros. Haven't had a chance to use them yet but I put them on the red truck yesterday, they look promising. I'll post some pics later if anyone cares to see the differences.