was closer to . Although it is much different from the original 1955-vintage Pontiac V-8 powerplant, the 301 has the distinction of being the last true Pontiac V-8 engine, as Pontiac ceased production of these engines effective April 1, 1981. From 1977 to 1981 there were 4 distinct 301 versions: 301 2-barrel (), (5th character of the VIN is a "Y" for 1977-1979). 301 4-barrel (), (5th character of the VIN is a "W" for 1978-1980, and the 8th for 1981). 301 4-barrel 'W72' or 'ESC' () (with the 5th character of the VIN being a "W" for 1979-1980 and the 8th for 1981). 301 Turbo (), (with the 5th VIN character being a "T". for 1980, and the 8th being a "T" for 1981). For 1981 model year vehicles, the engine codes are the 8th digit of the VIN. The 2-barrel version was last offered in 1979. The 4-barrel version was available from 1978 to 1981 and the Turbo version was limited to the 1980 and 1981 model year, however, it was originally intended to be available for the 3rd generation Firebird before its cancellation by GM. 301 Turbo The 301 Turbo was unique since it had a beefier block than the 1977–79 versions (which carried on in the non-turbo versions in 1980 and 1981), a very mild camshaft with lift and 250 degrees gross duration, a oil pump to ensure adequate oil to the oil-cooled Garrett TBO-305 Turbocharger, a rolled fillet crankshaft, a fully baffled oil pan, and a specific Quadrajet carburetor. This had extra-rich "DX" secondary metering rods and a remote vacuum source for the primary metering rod enrichment circuit to allow the Power Enrichment Vacuum Regulator (PEVR) to release the primary metering rods to move to the up position (enrichment) anytime during boosted conditions. This was to ensure there was enough fuel to cool the cast offset dished pistons. Boost was wastegate limited to . The 301 Turbo package mandated air conditioning, the THM350 (sometimes referred to as the CBC350 in various literature) non-lockup automatic transmission (THM350C lockup in 1981 Trans Ams), and 3.08 rear axle gearing. The 1980 301 Turbo was rated at at 4400 rpm and @ 2800 rpm. The 1981 301 Turbo gained the electronic controls with an O2 sensor, feedback ECM and E4ME Quadrajet providing a slight reduction in output to and .The 301 Turbo was limited to Trans Am and Formula