[68C15]

Tx Firefighter, with simple plugin reprogammer they can get over 900 ft lbs. although you need to strengthen the flexplate lugs on converter as they will shear off. imagine 12.9 in the 1/4!!!
the new ones with the improved injectors I havent worked on yet but the only problem I have seen with the older ones is injectors getting plugged with dirty fuel. at a cost of about $500 each just for parts. you have nothing to worry about with the heads. I had the heads off one that had over 200K miles & there was NO RING RIDGE. even still had the crosshatch on cyl walls!! some of them had a small crack in the fuel rail pressure regulator. keep in mind they run @ 30K PSI so DO NOT OPEN LINES WHILE RUNNING.
to sum it all up if I was in the market for a diesel I wouldnt get anything else than a Dmax-Allison
truck -GM engine-Isuzu fuel injection-Bosch
PS the reason the heads came off is somewhat embarrasing (lack of info & other shop incorrectly replacing an injector)