That looks like an ex-Alyeska pipeline machine...
Those were apparently exceedingly well taken care of, and if you're okay with the Detroit 4-53 Diesel, would probably make an excellent machine.
I do however take exception to the claim that it seats five. The cab is 52" wide. You might get three children across, or some petite women, but three normal sized guys? No way, and certainly not comfortably.
I don't have any personal experience with 1700 series machines, but if they're like the 1600 series machines, it looks like the front carriers are installed backwards. The 1300 and 1500 series carriers are symmetrical, but the extra length of the long track carriers (1600 and 1700) is not. On the 1600 series machines I've owned the extra length is positioned to the front (front carriers) and rear (rear carriers).
Forum member Firedozer (sp?) has one that's the same model and came from the same source. I'd suggest you sent him a PM for his thoughts (if he doesn't chime in).