Old Gold.....the size that you need is called a "group 24" battery. Buy the most powerful one that you can afford. The power is rated in CCA (Cold Cranking Amps.) Make sure that the battery you buy has the terminals in the right place. The positive toward to the fender, and the negative toward the engine. If you wish to have it look somewhat authentic, get one with a completely flat top, except for the posts. That way you can get a topper that replicates an original battery from 1959. There is a good discussion about these toppers in another thread in this forum......John