I don't have the upper with me, but I can tell you my friend bought it at a gunshow and the upper supposedly came from Sarco. It appears to be an original Airforce m16 upper, but has some unusual markings. There is no C or MP on the barrel, just a 12 on the bottom of the barrel near the flash hider. There are no forge marks on the upper that I could notice. The bolt carrier is marked with a D, not the usual C, and is a full-auto carrier. I didn't inspect the bolt, but it also was not marked according to my friend. The finish on the upper also was not the usual Colt grey, but some sort of dark grey/black anodizing with sort of a "rough" texture. The barrel and the upper also has the original style delta ring, not the current tapered delta ring. One more thing, the upper was not the "large hole" upper that Colt switched to for awhile. Sorry, I couldn't provide more details. I told my buddy I'd ask around and see if anyone might be able to help.