The blue and white Fords (Thousand Series) are very popular here in central Virginia as small-acreage farming and utility tractors. Right now, in this area, $6,500 is a tad high for a 3000 unless the tractor is in really good condition with good paint. Diesel models usually bring more money than the gas models. If it is in good working condition and you can get it for a little less, I'd go for it.
I'll second what was said above about the SOS tranny - VERY hard to find parts or someone who knows how to work on them. I would avoid the SOS "jerkomatic" right now. I had the 8-speed with 2-stage clutch live PTO, and it did all that I needed.
Also agree on the traction. I had loaded tires and still had to use chains to move much snow, which thankfully we don't get too much of here in this part of Virginia.