That is a S&S. Commonly referred to as "longdoors", these cars became quite popular when funeral directors found out they could trade their massive, gas-guzzling Cadillac coaches (many 1976 and older) for these smaller, fuel-efficient - and much less expensive - hearses. For many, the novelty wore off, however, when they came to trade these cars in on newer models and found out they were worth very little as used cars.
1983 was the first year for the extended side doors. Until then, a standard station wagon side door was used and the "stretch" was placed between the door and rear wheel. Even after the "longdoor" was created, a customer could still specify the shorter door, but relatively few did.