The Oldsmobile 350s made from 1968-1976 have heavy castings, beefier crankshafts, and better flowing heads. The 1977-1980 350s have lighter castings, including a thinner block with large "windows" in the main bearing bulkheads, and have crack-prone cylinder head castings manufactured by Pontiac Motor Division (castings are marked "PMD"; these heads were also used on the 260), and a lightened crankshaft. Some later versions of this 350 were produced with an analog electronic port fuel injection system, introduced in the Cadillac Seville of 1976.