ARP Head Studs - Click Link
ARP Head Stud upgrade—This is a durability upgrade and it increases the clamping force of the head to the block by 15% to 20%. We highly recommend the head stud upgrade on all diesel engines if available.
Now diesel engines make over twice as much power as they did 20 yrs ago, but the OE never upgraded the head bolt to a stud. The head to block fastener is under more stress than any other fastener in the entire truck so a stud is a vast improvement. The stud also puts considerably less stress on the threads in the block & it does not distort the cylinder bore as much as a bolt would, which can help with blow by issues. This upgrade is highly recommended if you do any heavy towing.