Repair-It

https://www.motortrendondemand.com/deta ... _r1xogdio/

Talk about being on the edge of your seat. This was awesome. Spoiler: they did not blow it up.

The good news is they pretty much did it as they should have. Stock Gen 4 bottom end with just an opened ring gap (mandatory). Everything above the block is for cramming air and fuel into it to burn.

I am actually not entirely sure what this engine started out as. LY6 truck 6.0L? Maybe. He said cathedral port but they are Trick Flow heads so that goes out the window when you change the heads obviously.

The LY6 is a Generation IV small block V8 truck engine with a cast iron block. It shares the same bore and stroke as its LQ4 predecessor. Like other Gen IV engines, it features variable valve timing. It generated 361 horsepower at 5,600 rpm and 385 lb-ft of torque at 4,400 rpm using "regular" gas, or ~87 octane. Redline is 6,000 rpm and compression ratio is 9.6:1. This engine uses L92 / LS3 style rectangle port cylinder heads, though without the sodium-filled exhaust valves of the LS3.
Applications:
2007–2009 Chevrolet Silverado HD
2007–2009 GMC Sierra HD
2007–2013 Chevrolet Suburban 3/4 ton
2007–2013 GMC Yukon XL 3/4 ton

It could also just be like an 04-06 LQ4, since that's around when the big rods went in (I think 04 was the transition year). A little confusing.