We ordered our 2006 GMC Sierra (see sig) in late October of 2005 as soon as the LBZ engine was available for the 2006 model year and took delivery on January 8, 2006. It came equipped with the LBZ engine for which I was adamant about having. We've had some of the usual minor issues with our truck but certainly none that have required major surgery. With relatively low miles on her,(84K) we have nothing but praise for our beloved "Silver Fox". I would NEVER replace her for our primary towing duties. Many times in recent years I've been offered nearly what we paid for her.
As for an LLY. I can only speak from the experiences of two coworkers who both have the same GMC 3500 truck we have only they have 2005 models with the LLY engine. Both have experienced overheating issues that ultimately required a larger aftermarket intercooler and radiator to correct the overheating issues. From what I've read over the years, the LLY is susceptible to overheating when towing heavy loads.
I'd question if the truck you're looking at is a 2006 model with an LLY engine in it. Few LLY engines to my knowledge made their way into 2006 model GM trucks. We ordered our truck in Oct 2005 and took delivery in Jan 2006 and it was built with an LBZ engine. That was a deal breaker for me...it had to have the LBZ engine. I did not want an LLY engine.
IMHO: Find yourself a truck that has an LBZ engine in it. Good luck.
Happy camping!!! See y'all down the road!!!:)
