In the 10K range, you get older. Capacities for trucks have greatly increased with advanced engine braking. Older trucks can still be found in very serviceable condition.
I would definitely look for a one ton truck rather than a 3/4 ton. If you find something you are interested in, post it on here and you will get many responses.
There is much to learn, and we are not motorheads either. The fact is, you have to learn to become a responsible owner/operator of a vehicle combination that is 45-50 feet long and weighs up to 20,000 pounds combined.