This may be a bit late in the conversation, but if you look at the way the notches and strips mate, I suspect that they are made they hold down the planks but allow expansion and contraction so they don’t warp. Just my 2 cents.
Phil Moderator, The Engine Shop, Interiors and Project Journals
1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum