Your asking a question about pay load. Trun it around this way. Some day cab box trucks can handle 18k class 6. Some candle handle 32k class 7.
That does not help you any more than the info you provided.
Ok your post says one axle= steer. And then 2 axle. I'm assuming =drives.
Ok now you got to find the gross vehicle combination weight rating. Just say its 32k.
Add tractor. 14k to trailer 10k. = 24k empty, subtract 32k - 24k. Gives you a payload of 8k.
This is just a example. This is why we are asking about your truck. Is it a box or a tractor.? No one is trying to mess with you.
If its a box. Fill the tank. Wiegh it, and then subtract that from 65k or what ever you mentioned. If its a tractor we now need to know what type of trailer are you going to haul.
My uncle once said. What's the color of the towel in hanging in my ex-wifes bathroom. Took me two years to understand the question.
In short. Depending on what he owes you, I would research the value and possibly sell the truck. Prices are stupid high right now. Good luck on whatever you do.