Here are a couple of photos I remembered I took of my '46 Chevy the day the cab was removed. I do not know if the '40 hardware and assembly is the same. The cab is believed to have never been removed previously. Judging from the rust and wear on wood and rubber bushings that would seem to be the case. Why the two hole plate/washer was used as shown, at the front of the cab on each side, is unknown.
The mystery Steel plate with two holes?
Cab to Frame Hardware '46 Chevy Half Ton