96 Cougar original battery!!!

My 1996 Cougar, 3.8 litre, finally has to be retired from regular use, has 139,000 miles, 3rd set of brakes, head gasket replaced at 130,000 miles, had regular service, and still has the ORIGINAL factory battery. Small things starting to go wrong with it so I think I am finally going to have get something different. I'm still going to keep it for local running around, can't part with it, been too good to me!!