'67 Merc 110, 9.8hp lower unit question

[gmarshall43]

I need to replace a gear in a 1967 Merc 110, 9.8hp lower unit. I bought another lower unit for parts. The guy I bought it from wasn't sure but thought it was from the early 70's and came from a 9.8hp motor. It looks exactly the same as mind with same length drive shaft and gear shift shaft. The gears inside are different. My gears are straight and the others are curved. Also the prop shaft is larger than mind. Will these gears work in my lower unit? I guess I will need to get another prop if it does. I can't use the other lower unit because it has a broke fin and has crackes in it.

Thanks,
Gary