Crowbie,

Look at the truck. IF it is a 96 or later, the motor was a Vortec head motor if it was a 1/2 ton, 3/4 ton or won ton. The bigger stuff is uncertain. Like the other guys say, look at the valve cover bolts.....center bolt or perimeter bolt. If it is a Vortec (96 up with center bolts) the heads are worth saving but you should at least have a compentent shop do a wow job on them before installing the things on your vehicle....you dont know where that girl's been so dont take a chance. If it isnt a Vortec motor, are your current heads shot/worthless/ugly? What is the benefit of the swap?

mike in tucson