Duke engine. The Postal Service specifications called for a 24-year service life and those with 2.5 L engine have surpassed expectations. 1982–1992 Buick Century 1982–1991 Buick Skylark 1985–1987 Buick Somerset/Somerset Regal 1985–1990 Chevrolet Astro Cargo Van 1982–1985 Chevrolet Camaro 1982–1990 Chevrolet Celebrity 1990–1992 Chevrolet Lumina 1985–1993 Chevrolet S-10 1985–1987 Chevrolet S-10 Blazer 1985–1987 GMC S-15 Jimmy 1985–1993 GMC S-15/GMC Sonoma 1985–1990 GMC Safari Cargo Van 1987–1994 Grumman LLV (USPS delivery vehicle) 1985–1991 Oldsmobile Calais/Cutlass Calais 1982–1992 Oldsmobile Cutlass Ciera 1982–1991 Pontiac 6000 1984–1988 Pontiac Fiero 1982–1985 Pontiac Firebird 1985–1991 Pontiac Grand Am Super Duty The Iron Duke block formed the basis of Pontiac's Super Duty four-cylinder racing engines of the 1980s, the last in a line of high-performance Pontiac Super Duty engines. The engines were featured in NASCAR's Charlotte/Daytona Dash Series, the IMSA GT Championship (in GTP and GTU class cars), and even in American Power Boat Association racing boats. Super Duty engines continued to be used in ARCA racing until well into the 2000s. In addition to parts matching the Iron Duke's stock 2.5 L displacement other crankshafts and their corresponding connecting rods were offered by Pontiac Motorsports, resulting in displacements ranging from 2.1 L to 3.2 L. A 2.7 L, Super Duty engine powered the 1984 Fiero Indy Pace Car to over during the race, but Super Duty engines were never available in factory-built GM vehicles. However, GM sold the Super-Duty-specific parts at authorized dealers and all of the parts required to convert a stock Iron Duke engine to a Super Duty version were available. Kansas Racing Products continued to make the engines in the early 21st century after buying rights to make them from GM. Cosworth also produced a 16-valve, double-overhead cam head for the 3.0 L version of the racing engine (Cosworth Project DBA, 1987). See also GM H platform GM engines References 1979 chevy Monza Brochure External links Jeep 151 information Iron Duke Gasoline engines by model Straight-four engines