I had heard some of the Chevelles came with Buick seats also. Must have been a surplus of Buick parts.

I dought it came that way from the factory Buick made that similar car with that body style but they had seperate plants. most likley it was changed later on the car.

Sources: JBTOYS Had a 79 Malibu wagon same body style found that olds,buick,pontiac had many enterchangable parts. That body style was from 1978-1984.