You need to measure the width, depth and height of your battery compartment first as it depends on these dimensions as to what battery will accommodate the space. Once you have the sizes then you could call this company below who's prices are competitive and will advise the best battery for your needs.
Thanks for your replies, its a 1998 and we are just dipping our toes in the water. We haven't picked it up yet but were hoping to get a battery that would fit before we do.