RCDs & M3 75mm GMC?

[Dave Block]

I do like this! The first and third vehicles appear to be M5/M9 half-tracks (which officially never had the 75mm GMC mounted) and the centre one is a proper M3 GMC. All sorts of little details set them apart, the lead vehicle has later headlights and side racks while the centre one has the earlier style lights, no racks and both are fitted with front rollers. The third is almost the same as the first but has a winch fitted instead of the roller, a real 'mix n match'. Obviously the placement for the RCA battery wasn't carved in stone either, 'somewhere along the side will do'.
Speaking of the battery markings, can anyone hazard a guess/definitively say what the RCD one would be in this case? I'm looking at Barry Beldam's 'RCA Tac Signs' Vol. Ed.1, 1995 and equating the 'Fox' name to Battery 'F' giving a basic blue square with the smaller red designator square in the lower left quadrant, white 'F1', 'F2', 'F3' or 'F4' depending. (Sigh, a picture really is worth a thousand words!).

Thanks again, Dave