Kevin,
I too recieved the 5/8th suprise on my 1965 Overlander. I wish it had been
3/4" because the 5/8 seems to be a little saggy in places when this 200lb
frame steps in the center of some of the wide spans. I had ordered marine
grade wood but then talked to some boat builders and was told that now a
days even the marine grade will have some voids in it between laminates.
They recommended an A/C grade plywood( a substancial savings from marine
grade). It has one good side for the floor and a rough side for the belly
side. After the floor was down I then coated it all with penetrating epoxy.
I'm sure that floor will probably out last me even though it does give a
little.
Earl Peck
1965 Overlander
Bellevue, Idaho