D6R LGP outside C-frame is a good tractor; bought ours new several years ago; never any problems. Rented an inside-C frame D6R unit; it had poor balance and tended to gouge while attempting to grade.
Anyway, gobs of power and w/ diff steer, is quite agile for such a large dozer. Worlds more power and weight over the smaller D6N LGP, which we also have. I welded tall grouser strips on ours and she'll spin both tracks, no matter. Our D6R LGP has the Paccar rear-mounted winch, that works well, except that the winch operation button on the joystick fails from time to time.