I came across this put out by GM about the 7.4L.

This large displacement workhorse has the torque to handle big jobs—towing trailers, hauling heavy loads and other weighty tasks—while providing the power, strength and endurance truck owners have grown to expect.

- Single-piece rear oil seal reduces oil leaks
- Reduced weight turned-skirt hypereutectic strutless pistons reduce friction
- Heavy-duty nodular crankshaft has deep-rolled fillets that are precision ground and balanced for smooth operation
- Steel camshaft and roller lifters on newer applications help reduce friction, improve wear resistance and increase low-end torque
- Revised lubrication system to reduce the possibility of oil leaks[/list]