1982 9.8HP gears issue

[KenOverton33]

I am re-sealing a 1982 9.8 HP gearbox. I need to replace the reverse gear but cannot identify the gear I have. I have ordered 43-63316 that is called for, but the inside diameter of the gear is too large for the propshaft. I ordered 43-48578 called for in earlier serial numbers, not knowing what the difference is. This gear is also too large. I removed the reverse gear from a 7.5 HP and it is a 43-63316. If anyone knows what lower unit I have or can help with identifying the gear I would be grateful.
In the attached pics, the gear on the left is from the 7.5. The middle bottom pic is the 43-63316. The gear on the right is 43-48578. The top middle gear is the gear that came out of my 9.8.

 

[KenOverton33]

Even though the gear ID at the rear is smaller on the original, I'm sure it won't matter, as the bearing is supported by the bearing carrier. I think it's odd that the gear was made different.