I comment on the lifespan, I just build them up new (I work at Peterbilt)

 

the new detroit is just a mercedes they bought them around 05 they keep the name alive for diehard detroit guys

 

thats interesting...I know years ago detroit was having trouble making the switch from 2-strokes to 4-stroke engines. in the late 1990's when I was driving big mining trucks, detroit was hooked up with a company called MTU because Detroit didn't make a large 4-stroke motor at the time

 

Detroit's 60series engines engines are pretty reliable, on par with cats and N14s, but the DD15s seem to be rather fragile, with crap stacked on top of other crap. I'm not much of a fan of Mercedes anyway,

 

Cat sold there on highway engine segment to Navistar, and they rebaged it the maxxforce. They just added a ton of EGR crap to get it compliant with the emissions standards. Cat still builds the internal parts for the engines, just not on paper and puts them in Navistar boxes. Gotta thank washington for all that crap!!!

 

If you want horsepower and more reliabilty out of the 2 options you might wanna go with cummins... Open then hood of a new isx its Damn near the same before the scr emission crap. Except there running a big azz fuel filter. Now the big bore paccar is a cluster f*** they put the air compressor above the starter.. pruning the fuel is a pain. It's a wiring nightmare thanks to DAF. And the mini paccar's are just rebaged cummins. If i remember correctly they came out with little paccar like a year or so before the big ones... and scr fuel emissions are also a cluster f*** I would stick with ole cats. 07 and older are good. 07+ cats with the spark plug(yes I said spark plug n i know what im talking about) can be iffy cause itll throw up a code for somthing that takes a couple of hours to find the route of the problem. But cummins is the new high horsepower/ torque. So cat or get a cummins!