If they are both the same teeth count then are they interchangeable? I looked them up on a honda/acura parts site and they are different part numbers but that dosent really mean anything. Anyone has any experience with this?

 

Just one gear? No. Gears go in pairs, always.

 

slightly different diameter, will cause clashing and lock up the tranny.

In fact due to the different diameters shoving the shafts apart ever so slightly, you will NOT be able to get the outer case installed.