My father recently passed and there was no will. Now my stepmother wants his remaining children to sign some form she sent to us regarding the sale of his pickup and travel trailer, we do not want to sign because we had asked her we wanted to keep these as areminder of time with our father. Do we have any real say over this?

Mostly its going to depend on how they were titled. Have you offered to buy her out on the asking price ? Is she selling to split the funds ? You could use it to make a down payment.

If your father died intestate then the rules as what happens to his assets are determind by state law. In some states the assets get split 50% to the spouse and 50% to the children, per stirpes. Not knowing where your father lived - let's assume that's the case here. So if the truck is sold you would each get a portion of the proceeds. If you really want to keep the truck, I suggest that you offer to buy out your stepmothers half interest.