pretty much all h23 parts are interchangeable. The head is the same, the block is the same...except for some small details that arent important. If your trans code is 'M2S4' then you have the h23a1 trans that came with it:
It's real close to the starter - if you look for it, you'll see it. Get it checked out and make sure the t-belt is okay. Chances are, it's fine, but its worth the look. The F22B timing belt is slightly shorter than the H23a1 belt, but the h23a1 belt is fine to use