Talking with Bowers at his Fort Campbell, Colorado-based engine shop, he says that the modified Gen III business is now booming and he wanted to showcase what could be done to make good, reliable power with a minimum budget. "I looked at it from a budget aspect, and I looked at the factory parts, the crankshaft and the counterweights and how GM put that engine together. I thought it was way more than adequate to make the power we were going to make. I thought if guys bought a used 6.0-liter, and they wanted to put different heads on it and bore it and they wanted an iron block, that it would be a great deal." Sourcing an iron 6.0L block as a core was easy, since they are turning up at salvage yards and eBay sales by the dozen. Bowers says that with the factory six-bolt main caps, the block would easily handle around 1,000 well-tuned horses, and with aftermarket steel main caps, could possibly handle 1,500. Those are big numbers for a stock block. With a target of around 600 hp, he just kept the factory caps and fasteners, though as they are torque-to-yield, new bolts were a must. Once the caps were mocked up in place and bearing clearance was checked, he found the oil gap in spec but on the tight side, so he just bumped it with a few strokes of his align hone, reducing the bearing crush slightly and opening up the oil clearance to just over two thousandths.

Melling's M-Select pump is generally regarded as the pump of choice for LS engines, and that was used on this low-octane 370. Two pump options are available for the Gen III engines. The 10295 pump is a stock-volume pump with 10 percent more pressure than an OE pump, and the 10296 pump offers an 18 percent increase in volume over the stock pump. Both feature hard anodized housings, steel gears, and a phosphate-coated iron rear cover for reduced wear. During the Gen III oiling system development, GM engineers had a tough time with the original oil pan designs because they were so shallow and close to the crank. Fortunately, with the resulting "batwing" pan and the truck pan, the majority of oiling issues were handled. The only major oiling system change that GM made was to enlarge the oil passage crossover at the back of the block from the '99 model year forward. Bowers says the oiling system on his 6.0L block was more than adequate for the task, so no other modifications were necessary. He tells PHR: "I didn't change passageways or restrictions, or anything like that. We used the stock truck oil pan, pickup, and windage tray."

Though some guys jump straight to a forged crankshaft for a high-performance buildup, the RED crew said that for the power levels they were running, a stock cast crank would do the trick just fine. With rolled fillets and lightening holes drilled to help move crankcase pressure between the cylinders, they have been known to hold well over 600 hp. The crankshafts used in Gen III Chevys were all cast iron but there were some minor differences. The 4.8 engine used a 3.268-inch arm but 5.3/5.7/6.0 engines all used the same 3.622-inch stroke. With rebalancing, all of those are interchangeable, similar to dropping a 305 crank in an early 350. The only major variance in cranks is that the 216-casting cranks used in automatic '99-00s had a rear flange that was about .860-inch longer than the more common 215-casting cranks. That could pose a problem for an engine/tranny swap. The factory cast-iron 216-casting crankshaft for this buildup was deburred and balanced, but was otherwise untouched.

Bolted to the factory crank was a set of Eagle lightweight connecting rods that came equipped with ARP's famous 2000 Series rod bolts. The advanced metal in the 2000 bolts is significantly stronger than the more common 8740 material, and not as susceptible to moisture and oxidation issues as the L19 bolts. With rod clearance at just under two thou, the guys had no problems with their recycled OEM rod bearings.