To get a GMC or Chevy 5500 you will have to go to a HD dealer. Here we have several dealers that are "truck" dealers, so buying the truck and the parts is no big deal.
You will get a T1000 Allison with the Duramax, there isn't an option there (unless you go manual). The Duramax is proving to be a good engine. We have put together about 25 GMC 5500 so far and very few problems have come up. I think the B Model Cummins is a better engine but I wouldn't hesitate to buy a 5500 with the Duramax. My only concern is I am locked into buying parts from one source, a HD Chevy dealer. The Internationals, Cummins, CATs, etc. I can get parts for at any truck parts supply house anywhere in the country. However, it's really just the principle that I don't like. I don't have much experience with the current MD engine offerings from Mercedes, but what I have seen and worked on, they seem like they are a nice package that delivers good power and reliability. The down there again is parts availability. Almost no place stocks parts for those Mercedes engines, so you probably have a down truck for a week.
There are quite a few things to consider, however all three of those engines are quite good and will provide good service as long as they are taken care of. Although it is expensive, I would recommend having the trans serviced immediately upon delivery with TranSynd so you get the upgraded warranty which I believe is still 5 years unlimited mileage.
You will get a T1000 Allison with the Duramax, there isn't an option there (unless you go manual). The Duramax is proving to be a good engine. We have put together about 25 GMC 5500 so far and very few problems have come up. I think the B Model Cummins is a better engine but I wouldn't hesitate to buy a 5500 with the Duramax. My only concern is I am locked into buying parts from one source, a HD Chevy dealer. The Internationals, Cummins, CATs, etc. I can get parts for at any truck parts supply house anywhere in the country. However, it's really just the principle that I don't like. I don't have much experience with the current MD engine offerings from Mercedes, but what I have seen and worked on, they seem like they are a nice package that delivers good power and reliability. The down there again is parts availability. Almost no place stocks parts for those Mercedes engines, so you probably have a down truck for a week.
There are quite a few things to consider, however all three of those engines are quite good and will provide good service as long as they are taken care of. Although it is expensive, I would recommend having the trans serviced immediately upon delivery with TranSynd so you get the upgraded warranty which I believe is still 5 years unlimited mileage.