Thanks for the replies and encouragement.
I have done business with the GMC dealer for many years. No paperwork
is needed, just a verbal agreement that I will buy the truck along with the spec sheet on the new one showing its price and my trade in value.
In Oklahoma the taxes are paid on the vehicle by the buyer. If I sell it the state has a one time excise tax based on the value of the vehicle, or purchase price, whichever is greater. It does not matter that I already paid the tax on it when it was new, it starts all over for the new owner. Then I get to pay the tax on the new one. No such thing as giving us a credit for the value of the one that has already been taxed if I trade it.
The last time I tried to sell a vehicle was about 5 years ago and dealing with the scammers and tire kickers was not fun but part of it, I guess.