Your best bets are under the back seat, under the front seat/s, inside the bucket seat backs, and up in the dash (glove box and steering column area).
I doubt a build sheet would survive Canadian weather on the exterior of the car (under/above the gas tank). The gas tanks barely survived Canadian weather!
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Prince Edward Island
'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.