When I worked at Repco*, the Exide range had a code system of sorts. For example, a typical Corolla battery would be an N310LP. Look at the battery with the posts closest to you. N = compact? 310 = size/model L = left hand positive P = pencil post
Whereas an N310 would have the positive on the right hand side, and thick posts.
*Ages ago and I may have forgotten, or this info may be useless in 2014