The Iron Duke Pontiac engine VIN code A (also called the 2500, 151, Pontiac 2.5, and Tech IV, though the decal on the air filter assemblies actually reads "4 Tech") is a 2.5 L (150.8 cu in) I4 piston engine. All Iron Dukes were built by Pontiac beginning in 1977 and ending in 1993. After this time, the GM 2.2 L OHV 4-cylinder replaced it across the entire lineup of vehicles that offered it. This engine is not to be confused with the Chevrolet 153. Early Iron Dukes had a Chevrolet V8 bellhousing (also shared with its third generation inline six) instead of the Buick-Oldsmobile-Pontiac bellhousing bolt pattern until the early 1980s when the later versions were installed in FWD applications where the 2.8L bellhousing bolt pattern was phased in. Cylinder head design had the intake manifold mou