Deceases gr.parents property being sold on the courthouse steps for back taxes. No Will. Should I pay them?will I be able to redeem

From your question, I have to assume no one has established a probate estate for your grandfather or grandmother. If you are in line to inherit the property, you should pay the taxes before the land goes up for sale on the courthouse steps. You state that you have always paid the taxes. If you open an estate in the probate court, you will file a claim against the estate for the taxes you have paid through the years.    If you are not in line to inherit the property, but you want the property, you should buy out the interests of the heirs who will inherit the property.  Then, you can establish the estates for your grandmother and grandfather, ask that you be appointed administrator and you can handle all of the affairs involved with keeping the taxes paid, negotiating with the DOT and ultimately transferring the land into your name.     This is very involved work and you should enlist the aid of an attorney who specializes in probate work to help you.