580b starter

First post here, have gotten a lot of great info already and hoping to get some more. I recently purchased two 580b’s a 73 and 74. The 73 is for parts. The starter is leaking oil. The fellow I got them from said he took the starter off the 73, knowing it was a dry starter and put it on the 74 which is a wet. It starts like a dream. I want to get a new starter but in checking the numbers the bad one is 1109143 and is a 10 tooth. Researching it does show it’s the correct starter for wet. The good one that starts the 74 is 1107584 and online shows its a nine tooth? The problem is, I’m confused now because in researching some say the 9 and 10 tooth can’t be interchanged but I also saw a video where someone did it. I need to know the 1109 is right before I have it rebuilt or replaced. Having a hard time finding a case dealer who can give a straight answer so hoping the group here will have the answers. Thanks