Normal. We rebuilt a '64 safari that had retangler wheel wells, I think your '62 was the last year for half moons on single axles. The metal inner wheel well has a flange that should mount under the plywood floor with sealer to help keep water out, a layer of fiberglass insulation then the plastic interior cover screwed to the top of the plywood floor. No idea why you are missing an interior cover on one side, have done 4 astreams seen others, all had plastic interior covers? Have seen some poor factory builds, it wouldn't supprise me at all that one was missing from the factory in 1962
. Possibly they figured that under the kitchen cabnets needed the cover to protect agianst things store there but not the other side?