1999 GMC Sierra 2500 Engine: 5.3L V8; Oval Port; Beaded Steel;. 1999 GMC Sierra 2500 Engine: 6.0L V8; Oval Port; Beaded Steel;. 2000 GMC Sierra 2500 Engine: 5.3L V8; Oval Port; Beaded Steel;. 2000 GMC Sierra 2500 Engine: 6.0L V8; Oval Port; Beaded Steel;.