Deere and Cat hate each other with a capital "H." I really doubt they would source a CAT engine on principle. I would guess the engine will be the Cummins QSX15 since Deere (with the exception of the ill-fated 8850 Springfield V8) has always gone to Cummins when they needed a bigger block (i.e. 6810, 6910, 6950 choppers, 8960, 8970 4wd). I wish they would come up with their own big block but I doubt they can justify the development cost.