The advantage of the 2 piece is you can use all of the existing components.
I dropped it off at the dealership, they did a consumption "test".
Basically they checked it and send me off and told me to come back in a week without adding any oil. I told them I would be back tomorrow because it used 1 quart in the 20mile drive to the shop.
The next day I drove it in and it was 2.5qts low...
They didn't graciously replace it. The service writer must have thought I was an idiot with the crap he was spewing out. I told him "you are going to replace it..."
I called the parts manager and then I called the OWNER of the dealership telling them the crap that the service writer was saying without telling the service writer. I told them if they want to scam buyers they should get a service writer that has a freakin clue about how an engine works... Both said, "Oh, the warranty motor, yeah should have the replacement (2 days later".
2 days later service writer calls and says you truck is ready and it will be $XXX. I told him I don't think so and that I would be there to get it. An hour later I show up and he gives me the ticket and I tell him, if anyone is going to pay that, it is you. He gets a little agressive and I ask to use his phone, he says sure. I dial the Owner of the dealerships cell phone on speaker and ask him why this guy is giving me crap. Service writer flips out! Owner tell him that there will be no charge and he needs to see him in his office. I went back a while later and he wasn't there anymore....
BTW, they make a good foundation for some good power, there is a tech article on where a mag started bolting stuff on it...http://forum.73-87chevytrucks.com/smforum/index.php?topic=8639.0