Okay, so, my skills have completely failed me. I spent the better part of 7 hours last night, trawling through every vintage Distinctive Unit Insignia I could find. Maybe its the fact that I stopped looking at around 0300, but I'm just not finding what I'm looking for.
And what I'm looking for is a particular DUI. It appears to be a silver eagle, on a silver base, surrounded by a silver wreath with a break over the top of the eagles head. Unfortunately, I only have hard copies of the photographs I'm using as reference material. I'll try to get some scans this week.
Here's what we know. Photo is dated to the late 60s (M16A1 w/ 30rnd mag, 3rd pattern fatigues), and is part of a series of photographs of my Grandfather at a as-yet-unidentified base, at the rank of SFC. He is working with a number of weapons, and is wearing a black beret (we have a color photo) with that particular DUI on the beret, and a shield-pattern SSI on his left sleeve, with another unidentified shield-pattern patch on his right breast pocket.
Any thoughts on what the unit might be? I looked through the better part of a thousand DUIs last night, and I've got nothing.