[Lynn Eades]

Do you have a manual?
There should be specifications in the manual.
Military vehicles were usually designated with an "off road" carrying capacity(GVM) which was conservative (for example the Jimmy 6x6 was rated at 2.5 ton for off road, and (essentially) the same truck as a 6x4 was rated as 5 ton, on road.
I think the authorities are now looking for the manufacturers ratings, and a manual with those specifications, should satisfy them.
I have found that the specs. changed during production, and providing the specs from the manual from the right printing, was enough to get me through.
My vehicle was a WC 54(?) 3/4 ton Dodge Ambulance, the carrying capacity went up from 15cwt to 18cwt,during production, so I used the earlier service manual specifications.
Good luck!