The "37" "Style" was a hardtop, which distinguished it from the "67" softtop and 2-door post cars (coupes/sedans) with several different style numbers. In 1949, Buick introduced a hardtop coupe. It used convertible doors and quarter windows, and was designated Style 4X37 (the X indicates Model). Those early hardtops were known as "Riviera Hardtops" (dad had lots of Buicks, but somehow I remember his 1951 Super Riviera Deluxe Hardtop). In 1962, the hardtop designation changed from "37" to "47," and they became known as "Sport Coupes." Several years later, the "37" and "hardtop" designations came back...and at this point I lost track and became thoroughly confused...:laugh:
The 1971 GM Buick Master Body Parts Catalog actually calls Body Style Code No. 37 : "2 Dr. Hardtop Coupe"