What is his DOT and MC number.
If he can not give you BOTH of these he is not licensed and may not be insured to haul your tractor.
A guy that goes threw the trouble to be licensed will have proper insurance and can usually be trusted to be a good carrier.
Even if 10 people tell you they have used this guy and he was straight up with them; you may be the guy he is hauling for when he has his first major accident. If he is unlicensed and or uninsured you just became the first unsatisfied customer.
Once he gives you his DOT number you can look him up at the link below.