I have no idea of the exact age, but she wasn't even in her 60's when she started on it. The problem was they mishandled her trust and that put her over their income requirements at the time. Disability said the car (Which was less than 4 years old at the time.) and the pittance she got because the money was mishandled by a family member that wasn't happy with stealing all my GG's gold, silver, and jewelry; all while saddling my grandmother with the transport fees to get the car from CA from TX and the mechanic fees to render it drivable again. Like I said, it's not simple.
You don't get disability for being old, you get it for being too sick to work. Provided you worked long enough in your lifetime.
http://www.ssa.gov/pgm/disability.htm
Edit: I phrased that other statement badly. It was not because of old age; she was on disability because of how young she was at the time. She was too young for regular SS.