[gmc684x4]

I got mine from summit then after I found i could have got them from skogen with machine work and upgraded springs for higher lift cam

I have gotten a like new set from ebay and picked up a free express van that the po was determined the heads where blown really bad intake gasket good motor and tranny for free

The l31 had a very bad intake gasket that failed often and is most likely the cause for vortec heads to crack from overheating to many times with no antifreeze