1996 GMC C2500 Engine: 7.4L V8; with 124 / 140 Amp Alternator; with Air Pump; without Air Conditioning; Position: Main Drive;. 1997 GMC C2500 Engine: 7.4L V8; with 124 / 140 Amp Alternator; with Air Pump; without Air Conditioning; Position: Main Drive;.