I have a older golf cart that is only used for a few days at a time three times a year, 36 volt. What batteries are good?

Your best bet with a golf cart is to replace the batteries with the same size and voltage as you have already. You want them to be very secure in the cart. If they shift, they can cause the cart to become dangerously imbalanced and either veer into oncoming traffic or roll over on a hill. Both options are painful.