Lots of misinformation here. Split phase is used to identify 120/240V power. The QD 8000 is not 120/240V but rather 2 120V circuits. This means each hot line will carry 4000/120 = 33A and the neutral will carry the combined current of 66A. You may need to replace the wiring from the gen to the ATS and then to the CB panel. And you will need to upgrade the ATS to one that will handle the increased neutral amps.
Besides physical placement and weight your biggest problem might be diesel fuel. You need a separate fuel pickup and return to the tank. I would not T into the existing engine lines. This means the fuel tank will have to be removed and upgraded. Be sure the gen pickup is higher than the engine pickup so that the gen can never empty the tank enough so that you can't run the engine to go get more fuel.
Or you could install a second diesel tank for just the gen.
12V to the gen is needed of course and you might need larger wires for starting. Check the gen specs vs your existing wiring. And you'll want a switch panel and wiring harness for inside gen operation.
This will be a major project.
