I would say an early International TD25C. It has the rounded bullnose, unlike the earlier TD25B which had more squared off corners. So that would put it in the late sixties I believe, maybe even the early seventies. The roller frames and the lights are also dead give-a-ways that it's an IH.
Maximum lift capacity would be about the same as a 583H from the same era, which is to say about 130000 pounds, probably with an 18 to 21 foot or even longer boom. Tractor weight was about 78000-85000 pounds, with an 18000+ pound counterweight. Horsepower probably about 285.
As a pipelayer, this machine would likely not have seen heavy use. Pipelayers last for centuries it seems like because of this.
This tractor is also set up for some adverse weather conditions. Cabs on pipelayers are rare in this country, more common in Canada and Russia. I notice the counterweight is dismounted as is the boom, not uncommon as this would have been required to move the tractor around on the highway. They may be stored elsewhere in the yard where the tractor is.
As an International, the price ought to be fairly low compared to a Cat, and if someone need a good heavy pipelayer, it's probably a steal, so long as engine, transmission, steering and brakes, draw-works, and finals are OK.
As for booms, if it is missing or badly damaged, there may be some booms that would fit this tractor around somewhere. Give Scott Jeter a post at;
sjeter@sidebooms.com, Scott's a great guy to talk to and very knowlegable.
You can also find some information at;
http://www.midwescoind.com
Also: Midwestern Manufacturing Company
P.O. Box 3445
Tulsa, OK 74101 USA
2119 South Union Avenue
Tulsa, Oklahoma 74107 USA
Phone 918-446-1587
Fax 918-446-6384
sales@sidebooms.com
Or:
http://www.sidebooms.com/contact.html
All of these should get you in close.
Good Luck!