1981 Mack MR Engine: 11L -6 DIESEL; Position: Air Conditioning;. 1982 Mack MR Engine: 11L -6 DIESEL; Position: Air Conditioning;. 1983 Mack MR Engine: 11L -6 DIESEL; Position: Air Conditioning;. 1984 Mack MR Engine: 11L -6 DIESEL; Position: Air Conditioning;.