They might not rebuild it locally. With our Yanmar, he said it was better to pull the transmission and send it to Mack Boring, they either rebuild yours or pull one off the shelf and send you a rebuilt one that comes with a warranty.
The labor and cost is less than or equal to someone doing it themselves locally.
Anyway, he's the guy that services our boat and is a very decent, straight shooter. Call him, he'll give you his view of what it might cost, how long it should take (varies depending on when you arrive), etc.
Chris Oliver
Portside Marine
(410) 263-3302