Yes. Would those have been issued for an F-1? I expect the truck plates were only issued to larger trucks, but I'm not sure. Maybe they did things differently back then.
The cutoff has generally been 6000 lb GVW. It's only a gut feeling, but anything rated at 6000 or higher would have been considered a truck, so yes, an F-1 would have had truck plates. My only experience was Colorado, where an F-1 wore truck plates
Couple of ideas to throw out - may or may not help.
Before 1942, half ton pickups were build on car chassis. Beginning in 42 Ford started the typical "truck" chassis even in pickups. They were only considered half-ton trucks.
In 1948 Ford started the "F" series.
F1 half-ton gvwr was 4700
F2/3 three quarter ton gvwr was 6800
So while I don't know the answer for sure, it is my belief that T plates were issued to half-ton pickups 1942 on. But, this may have varied state-to-state.
Decided to keep it simple and go with the normal tags.
Not surprisingly, the DMV had no historical information and could only offer the current guidelines which offer truck plates to pickups over 6500lbs gross weight.
I suspect the guidelines were different back in 1949.