We are looking at a 2001 Ford F250super duty super cab long bed V8 7.3 L Turbo Diesel Auto trans 4WD w/ 98,000 miles for $18,000. Will this pull my 3 horse aluminum horse trailer w/LQ gooseneck that is 8500 lbs empty and 13000 lbs loaded? Also is that a good price for the truck?

That truck is rated around 12000 + towing and should tow it. Make sure the trailer bakes are good and good trailer brake controler. Being on the edge of capacity, be sure to change your oils including transmission more often. A heavy duty 3/4 ton truck can tow at it's capacity, while a 1/2 to should be closer to 75-80% of capacity especialy with horses. The price sounds right, but look up similar trucks at www.autotrader.com