i'll third the cummins.... there is less parts, electronics and the parts are cheaper. Not to mention just how solid the cummins block is.

 

The Cummins is ok but I'm a V-8 diesel fan. Plus I thought I read some where that you have to put a 2" body lift on to install a Cummins.

 

2" body lift is required for both a Dmax and older style Cummins. If you want the new Common Rail cummins it requires about 3-4" body lift.

 

I remember watching a Charlston Traction Company video and they said the Cummins is only 4 cylnder and 155 HP, so what draws people to it? fuel efficiency? torque?

 

If you couldn't go all the way with the duramax, I can't see changing from the 6.5. At least you could continue to get parts for it out ofthe AMGbook on the H-1, vs. having a one of a kind set-up.

 

For the 4bt like the one installed in his rig I believe it was fuel efficiency, reliability, simplicity(less to go wrong on the trail since its all mechanical), and easy to work on.
As for the one like seen in Andres 2dr with the Common Rail 6cyl you get power, torque, reliability, and simplicity(vs the Dmax). with just a $300 computer upgrade you can get 500hp+ out of these things. And still it is easy to work on you should see his engine bay its empty so empty he could fit a winch under the hood and still have enough room to chop like 6" off the front of the frame and hood.