Trail Boss 325 Carburetor … which one?!?

So, I just bought a 2000 Trail Boss 325 and I need to get a rebuild kit/non-OEM carb for it.

… buuuuut when I go look for one the sites always ask for one additional piece of information: A00AA32AA, A00AA32AB or A00AA32CA

I’m, like, "uh … what?" I don’t even know what that is to indicate or how to find out which one is right for my machine.

Any idea how I can determine the right A00 number? … annnnd what’s the A00 number represent (out of curiousity)?

Thanks in advance for pulling my head out …