Lower: Pre-AWB Colt, marked "AR-15 A2 Gov't Carbine." I swapped out the screw-type pivot pin for the regular style. The lower is a take-off from a complete Colt rifle, so I assume all the parts are Colt. It has the 2-position only receiver extension and old style extension nut with the spanner holes.
Upper: Assembled with a new C7-style receiver from Brownells, a Colt 1997 dated barrel, ADCO spacer to get the flash hider+barrel to 16", pin and weld. Optic mount is a Colt-marked piece I got off Gunbroker with the period correct Weaver slots.
Optic: Aimpoint 5000 from Ebay. They're not as hard to find as many think. Still works like a champ.
Light: Surefire 660, also ebay. Mounted on a section of rail screwed through the handguard. Many folks use the barrel mount and mine came with one, but the handguard mount seems much more prevalent with the Delta CAR-15s. I think the barrel mount was more of a Ranger thing.
Sling: Standard USGI silent sling with LC-1 pack strap adjuster added to give quick adjustment like a modern sling. I haven't seen the LC-1 adjuster documented in Mogadishu photos, but someone who was there came out with a sling like that later so I'll call it "correct." Most of the Delta guys seemed to be using two silent slings spliced together to make them longer and presumably more maneuverable.
Here's a better photo of the lower. I was lucky to find this for a really reasonable price. It has the correct magwell markings, the period correct A2 profile, and no MILITARY AND LAW ENFORCEMENT ONLY caveat on the right side of the magwell, which would not have been on a gun prior to 1994.