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.