Steveg Does NJ let farmers have truck on the farm without titling them? They do here in Michigan. Theses truck can not go out on the roads that would be illegal. However if the truck stays on the farm it doesn't need to be titled. If NJ has a similar law then all you should need is a bill of sale from the last buyer. Just don't tell them he is in another state. Just state that the truck was used on a farm and not titled. You may need to have it inspected by the local police but that is simple.
Good luck and I hope this helps