We have physical evidence and documentation that 3/8" square drive tools were also used by the US Army Ordnance Dept, Bill.
The March 1945 ORD 5 SNL J-4 lists 3/8-inch drive pieces (bars, handles, sockets, deep sockets, swivel sockets, and universal joints) individually. Most of the spec citations are TAC ES No. 702a. But some of them are Snap-on F (for Ferret) model codes.
It also lists three 3/8-inch square drive sets.
One of those sets is 41-W-2616, a 13-pc set with a rat, hinge handle, extensions, uni joint and eight (8) sockets. If that FSN sounds familiar, remember that 41-W-2615 is our precious GMTK (MVM/GM TS) midget set. It has a TAC ES No. 702a in the spec column.
The second set is 41-W-2616-20, a 20-pc set with the standard 13-pc complement of pieces, plus a DLB, a speeder, a sliding tee, and a few crows feet. It has a BFT-TD-12 citation in the spec column, which is the code for a Bonney TD-12 set. I'm pretty sure that's the same or similar 3/8-inch drive set that's in the back of the multiple drive size Bonney Master Mechanics Kit in back of the Dodge WC41 Emergency Repair Truck, listed in SNL G-61, which is early, and doesn’t include any FSNs. Dave (daveus6) would know better.
The third set is inside the 100-piece Blackhawk Master Set (41-W-2613-500, BKM-100W), which went in a big wrecker, at the very least. Those are shown in itemized form in the various sources (1944 TM 9-767, 1939 Shadbolt 7 Boyd catalog, March 1945 ORD 5 SNL J-4) that I included in the Blackhawk Master Set, linked here.
Please post a close-up of what this mark looks like, Roger. And please check your PM.Silly's MB wrote: ↑Fri May 11, 2018 5:24 am...but the majority of these are marked with the Canadian acceptance mark.