you can go to any auto store ,,sears napa any one can tell you the correct size of the factory Batt.. I have beeb doing a test with a small batt, 400cca and for a month now it is working great it weights 12 lbs the stock batt weights 40 + lbs, and is 690 cca. the size is so it fits in the space and can be bolted down, see this .------------ https://www.crossfireforum.org/forum...tery-test.html ------- jim