I've never replaced it in the boat, but I'm fairly certain you can. There is a snap ring, but once removed the bearing isn't hard to pull out.

there is two bearings one gimble and one tailstock outer yo[u can do in the boat but if the inner bearing is bad I believe the motor has to come out well thats how I had to do it..maybe im wrong.

Is the bellow replacement covered in the TRS manual? Want to make sure we do it correctly. Definately would like some instructions instead of just guessing on what needs to be done.

There is no gimble bearing in a TRS drive.
Yes bellows replacement is covered in the TRS service manual #5. Do you have this manual?

thanks, yes i found the pdf.

I ran into a similar problem with mine this weekend. Hauled out and noticed a small oil leak in the driveway...Found a hole in my bellows The rubber felt very spongie and I was convinced I puked a drive...I was relieved when 3qts of clean green fluid drained out. Pulled the drive and the bellows was full of water/tranny fluid. Drained my tranny and it had some water in it but only pulled out 2 qts (merctrans). I suspect I have been leaking ATF out the real seal and that compromised the bellows...and the water in the tranny got sucked in on the last boat ride....I might have caught it in time to save the tranny...It wasen't slipping yet. I still need to pressure test the cooler to be sure. Debateing pulling the engine to change rear seal.

If your sure there was tranny fluid in the bellows than you really should change the rear seal. That seal is NLA from Merc but you can get them elsewhere cheap. I think their about 8 bucks. I have a couple of them. If you need the seal number let me know.