If a dealership ask? Me to sign form 4506 t request of transcript from IRS. For 3 years .do I have to sign.

No, you are not required to sign, I assume this is a dealer where they are going to finance it for you. So if they require this for credit, they will not get a loan most likely. So you will need to go and get a loan though your bank or credit union and just buy it from them.