Riviera — E-body (1983–1985)

Wikipedia's Buick V6 engine article gives LD5 as the code of the 231 and lists the Riviera S-Type, T-Type and convertible for 1979–1985 under that section, which covers the turbocharged engine as well as the plain one; its Riviera article names the 231 and the turbocharged 231 for the generation; no Riviera source ties the code to the plain or the turbocharged engine, and gnttype.org's Riviera blocks do not print it; matched to the car by meaning

the 252 V6 (VIN code 4); Wikipedia's Buick V6 engine article prints LC4 and lists the Riviera for 1981–1984 and its Riviera article names the 252 as the standard engine from 1981; gnttype.org's 1984 Buick VIN table prints LC4 for the Riviera Luxury, a second source (owner ruling, 2026-11-05: a T3 page that names the code for the nameplate, with Wikipedia dating every year), its 1983 table repeating the 1984 one, so 1983 rests on Wikipedia's dating; 1985 is left out because the 1985 NICB Buick engine table prints VIN code 4 in its 1984 column but not in its 1985 column and Wikipedia's article gives the engine through 1984

the Oldsmobile 307 V8 (VIN code Y); Wikipedia's Oldsmobile V8 engine article prints LV2 and lists the Riviera for 1980–1985; gnttype.org's 1984 Buick VIN table prints it for the Riviera convertible, a second source (owner ruling, 2026-11-05: a T3 page that names the code for the nameplate, with Wikipedia dating every year); its 1983 table repeats the 1984 one and its 1985 Riviera block repeats the 1986 one, so neither adds a year

the Oldsmobile 350 cu in diesel (VIN code N), optional; Wikipedia's Oldsmobile Diesel engine article lists the Riviera for 1981–1985 and its Oldsmobile V8 article names LF9 as the 350 diesel; gnttype.org's 1984 Buick VIN table prints LF9 for the Riviera Luxury, a second source (owner ruling, 2026-11-05: a T3 page that names the code for the nameplate, with Wikipedia dating every year), its 1983 table repeating the 1984 one; the 1983 and 1985 NICB manuals print VIN code N (the 1983 manual in its 1982 column and not its 1983 column), so those pages do not show the code