I own and operate 2 of them and know them inside and out. What specifications are you looking for? They are 200hp and the nicest snowcats they made in the day for large grooming jobs. Maintenance and proper set up are extremely important( like most snowcats) and parts are readily available and no more expensive than excavators, dozers, dump trucks etc.
I'm pretty adamant about proper maintenance as I am often in very remote country and I have found with every single snowcat I have bought that they needed a thorough going through before I would take them out on the trail. Bombardiers, Thiokols and Pisten Bullys. I would count on that with the one you are looking at also.
You should be able to find a hydraulic mechanic who can check your pump pressures which will help determine the condition of the most expensive part of the cat.Track condition is another area to look at as those parts can be expensive(like all snowcats).
Safety One usually has the spec sheet available but I see their Pisten Bully page is under construction. What all do you want to know? I have all the available manuals for those machines.