Interesting combination of engines: 2 12V Detroits, and a blown Chrysler Hemi. I like the weird stuff, and European tractor pulling has it. Rolls-Royce Griffons, Rover Meteors, big radials, Allison V1710's, etc. Run what you brung, and hope you brung enough. American tractor pulling has gotten too uniform, with everybody running 4 Chrysler Hemi's.
The most awesome pulling tractor I ever saw was probably the Banter Brothers modified with 7 blown big-block Chevies running in the 12000-lb unlimited class. After they came out with that one, the NTPA lowered the weight limit for the Unlimited class to prevent using so many engines.