They are pinned. When I bought the boat, the stb one leaked. Pulled the carrier, new o-ring and it lasted a few trips. Then I broke a DS on the port (LH) one. That was a bear to find parts for. Ended up buying another gearcase and transplanting the parts. Got 2 trips on that one and now it's leaking.
I'm just not going to keep messing with them. CLE's here I come.