1965 Seat Measurement Question

I measured my cars. The space is between 3-1/2" and 3-3/4". Looks like it depends on the upholstery and foam buns. The piece of wood in the photo is exactly 3-1/2" long and will stay between the seats of one car if placed carefully. My gold car is a full 1/4" wider at 3-3/4" and my othger one with red seats is just between those two.

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