That's what I was thinking. Looking around the net, I discovered references a U90 (pre-2002?), but I have yet to find a photo or description in the old catalogs (thanks, Tim58hsv). I've found the U-100, etc - all with the incorrect # of elements.
So I figure it lies somewhere between a U-75 and a U-100. But since I scanned the radio shack catalogs from the 70's thru the early 2000's, I have to assume it's NOT a Radio Shack.