Having now disassembled a few AD trucks over the past years (and reassembled two of them

) ... Every one of them, including the '49 3804 in the garage, had the pair of bolts in the center at the bottom. See the attached photo for their corresponding holes in the front cross member. There are two wider set holes and maybe someone can tell us what those are there for, but I've never seen them used for anything on any of the Chevy AD trucks I've personally dissected.
Picture shows the original spacer and re-enforced rubberized gasket (or whats left of it) sitting next to the holes. The bolts came up from the bottom and threaded into the bottom of the radiator support. This truck had not been disassembled since it was built.
Hope this helps