As far as comparison..
LB7, known for injector issues, the more filtration you add to your mix the better your chances of prolonging the removal/replacement down the road (which is inevitable) Lb7 trucks have no emissions unless it is an old fleet truck/ CA emissions model, so egr is not an issue, and the pcv system was actually effectively done on these models so the pcv reroute is not completely necessary. Just plan to have around 3-5k sitting around just in case for injectors, depending on if you do it yourself of it you pay to get it done. However these are great motors, and you can't beat the sound of a straight piped LB7, its what all the duramax guys go for sound wise.
LLY, known for head gasket issues. This is about a 2kish job depending on the parts you go with. The 05's seem to have a few less issues with this than the 05 models did, however depending on how it's been run/beat on this has to be on the back of your mind. When doing the r2, just bite the bullet and go with arp studs so you won't ever have to do it again down the road. They lly rigs have a variable vane turbo, getting rid of the wastegate the lb7 trucks had. GM improved their injector issues, and the only thing you have to worry about in that category for the lly rigs is the injector harness, otherwise known as the "icepick fix". I should also add in the restrictive factory turbo mouthpiece, as they are very poor for air flow. They are very strong engines and can go maintenance free for many miles (just like any diesel really)
Either truck you will be happy with as they are great rigs :thumb
