I bought mine on black Friday last year for 13k under sticker, because no one wants a stick anymore. Had been on the lot for 6 months. G56 has 350/660, base auto has 370/800, and the HP version has 385/850. I have 34k on mine and been back to the dealer twice, one for gelled fuel because, even tho they install a rear fuel heater, they don't turn it on in software (and the filters are very low micron), and this past summer at 25k it needed all 4 balljoints, left front shock, and the intermediate shaft. Was surprised at all of that but not much I can do, I attribue it to the really shitty rt 24, 128, and 495 roads I drive 120 miles a day on. Mine is a SLT crew cab so nothing too fancy but much better ride and a lot quieter than my previous 99 cummins.
Personally I've never been a Duramax or powerstroke fan, I had good luck with my 99 for 110k miles and so far, really havent had anything I'd consider horrible on this one. The exhaust brake works awesome to speed up warm up, I can have heat within 5 minutes when its 20 out.
There were early DEF system issues but 95% of it was software bugs, which is expected with an all new ECM. Thats almost all been worked out, and I never had issues. My DEF usage is rather low because I do mostly highway and it keeps the filter clean.
I will say this, the capless fuel filler is the dumbest thing ever designed. It has two flaps and whatever fuel gets trapped between leaks all over the ground (which happens almost every fill up). Id like to swap to the 2010-2012 filler setup but haven't had time.
