2008 GMC Sierra 2500 HD WT 8 Cyl 6.00L
ENGINE SWAP NO SPARK
I SWAP MY ENGINE OUT OF MY 2008 2500HD 6.0 TRUCK AND INSTALL A 2009 CHEVY SILV 2500HD .6.0
Read fault codes and repost. Of course I could say double check all your connections and ground wires. Often when an engine is removed, ground wires that were unbolted often at the rearmost part of the engine sometimes get forgotten to be reattached. Depending on what wire, yes you will have no spark. Look for a loose or unattached wire especially at the rear of the cylinder head area.