Unless he has a straight 6, it would have to be two bad cylinder heads. And unless some thing really bad happened (ie overheated the truck really bad), thats kind of unusual.
Pete
'83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
'97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd