Jeremy, I just changed all the coolant hoses on my 2003 era C-12. Most looked OK and probably were but one was a disaster just ready to happen. I do not know how to send picture on Forum or I would. With the new thermostat from Cat, lip seal and gasket it was about $75.00. All the hoses I procured from NAPA, Gates hoses, plus 7lb Radiator cap ran about $230.00 at our business cost.
The thermostat was the old design in my coach so I take it it was never replaced. We always ran for the last 3 years 50,000 miles at around 188 - 192 degrees. At steep grades we would get up to 204 degrees. We always have pulled a Ford F-150 Crew Cab and much of the time I have it loaded with fire wood and a fire pit or numerous other purchases or items found along the way.
The new series thermostat design from CAT has eliminated the sometimes problem they figured they had when it would not fully open.
From my experience it is not an impossible project but it is a lot of work. You will have to remove some (coolant tank), or unhook some items (alternator) so you can even get at hoses and then you need to be ambidextrous. Took me hours to just get the hoses off and then go order and put back on. I did replace all the clamps from the in my opinion mickey mouse screw clamp to a T bolt clamp. One T clamp is equivalent to at least 2 of the screw clamps and no leaks. The T bolt clamps are a good deal higher than the screw clamps.
I am not sure about your configuration on your Cat but from my 1991 Contessa to the 2004 Marquis I do not see a lot of difference with the coolant hoses ( I changed them on it too). Can get you all the part info if you so wish to have. If you have CAT do it I would surely be interested to know what the cost is. I would be willing to bet it takes them 8 hours of labor. Remember, from what I know they will not have any of the hoses as they did not supply this, Beaver or whomever made Beaver supplied these parts.