Yea, this tractor is in excellent condition, but I'd just like to know a year model. It only has 590 hours on it.
You'll be very happy with it. For most of my uses, the
B7100 (an HSD, like yours, but with a Woods FEL, supposedly a '98 model, which I had before my
B7610) is every bit as capable as my
B7610. In fact, in many cases, it was better, as it used about 2/3 the fuel. The main reason that I traded up to the
B7610, was I wanted/needed more 3PH lift capability, as I move firewood pallets with it. I also wanted power steering for FEL work. The fact that I found a killer deal helps too.
If you do trade up, the
B7100's definitely hold their value. I got more for mine that I paid for it. In fact I sold it for not a lot less than I paid for the
B7610 
590 hours is very low. My first
B7100, a 1980 gear-drive unit had just over 2000 hours, and was still very strong, and didn't leak or burn oil.
In today's HP focuses world, 16 engine/12 PTO HP doesn't sound like much, but it got the job done. I did lots of post holes with mine, and also ran my 53" yanmar tiller. It did fine in both tasks. It also ran a 60" MMM very well.
It used between 1/3 and 1/2 gallon an hour of fuel, maybe a little more mowing.
Maintain it, and enjoy it for many years to come!