Bucket seats were a really big deal in 1963 and were standard on Cutlasses. To amortize costs, GM forced Buick, Oldsmobile, and Pontiac (BOP) to base their '61 to '63 compacts on the rear-engine Corvair platform of 1960. It's true. Each division employed a different strategy to adapt the driveshaft to the nearly flat, Corvair-sourced floorpan. A small-diameter, curved driveshaft delivered power to the Pontiac's rear-mounted transaxle, while Buick and Oldsmobile employed small transmission cases and unique rear axles with the pinion set at a very low angle. This allowed the driveshaft to be mounted lower. If you compare the surfaces found inside a Corvair's trunk compartment (up front), you'll see it shares numerous sheetmetal stampings and suspension parts with the front engine BOP compacts.