As Bill said, the driver's seat is the original seat but the passenger seat is not. The passenger seat should have the ribs on the back.
That foreign seat is not the 47-55 Suburban passenger "jump seat", which has a tubular frame.
Bill's suggestion that the seat might be from a Sean Delivery sounds good. Does anyone have a 1947-53 Restoration Pack? There may be a picture of the Sedan Delivery seat in there (the driver and passenger might be the same style in the Sedan Delivery).
The picture of a Sedan Delivery seat in the late '54 documents is a picture of the new '55 Sedan Delivery body style and they are different from the seat above.
By the way, if you look at the third picture above, it looks like the passenger seat base allows for the entire seat to rotate forward (but, the seat back does not flip forward). Those legs in the back must have punished the floor when the seat was rotated back to the floor.
