Texas does a title only transfer and no one cares about numbers. If a running vehicle is brought into Texas from out of state, a licensed inspector must do a safety inspection and compare numbers on the title. I have been a licensed inspector in Texas for many years and the regulations are silent as to where the number has to be on a vehicle manufactured before 1981. Just go to your county tax assessor, collector with the old title and a signed and dated bill of sale and pay the 6.25% sales tax and you will be fine with a title only transfer. I am assuming you already have a blue Texas title in your name. If that is the case, it is your vehicle, and you can do with it what you want.