I have a 1995 explorer xlt. It has about 102,000 miles on it, and seems to be running fine. I have always changed the oil every 3000 miles, and I was wondering if there is a need to change time timing belt or chain [I don't know which it has] at a certain point in time. People have told me that if this belt breaks, it can ruin the engine, and I'd like to keep the vehicle for at least 2 more years. If I should change it, how much should this cost? Thanks for your help and advice.