As a set they were very useful, covering passenger vehicles and several trucks from 1/4- to 2.5-ton. The makes I have had in my GMTK's have been either Walden and Snap-on, because they are the most practical to find. Not common, but they are out there. And there are Thorsen sets floating around with FSN's on the carboard box they came in, which are harder to find with or without the box. If you're curious I can save you the measurements. The 1129 is 47/64". The 1130 is 15/16". And the 1131 is 1-3/16".
I've posted this claim before, and I'd have to find that or double-check my notes to back myself up again, but the most interesting thing about the GMTK drag link bit set is that it doesn't appear as a set in many (if any!) catalogs that I can recall prior to WWII. The 1130 appears in Walden's 1940 catalog by itself, for example. They were making an 1129, but it was a screwdriver bit, not a smaller version of the 1130 socket. And no 1131. Similar situation with Snap-on as I recall.
In short, while I can't definitively prove it, I attribute those particular sizes showing up as sets to wartime Ordnance Dept specs.