I know the gmc has a 347 pontiac v8, but the 4 spd trans won,t stasy in second. So I,m hoping the chevy 4 spd will work. also the 2spd rearend in the gmc doesn,t work. Lots of little stuff. i USE THE GMC EVERYDAY IN MY CONSTRUCTION BUSINESS, IT HAS 42968 MILES ON IT AND I REALLY WANT TO KEEP IT LOOKING AND RUNNING WELL. i can purchase the chevy 40 series with v8 for $500.oo and figured it would be a good donor. thanx guy