I'm reviving this thread with an update and some questions.
I decided to hold off on replacing the bellows. I inspected them thoroughly, and I could not find any spot where it looked like water could get in. The clamped ends looked good and I saw no tears/puncture. The rubber was still soft and pliable.
Just last weekend, I reinstalled the drive (it sat in the basement over winter, where I changed the impeller, replaced the gear lube, and pressure-tested the drive). Drive was installed with new OEM gaskets/O-rings, and new nylock nuts per Grub's suggestion.
I had the boat in water this weekend, for about 3 hours. It ran flawlessly, and I saw no water in the bilge. About 48 hours after I returned home, I pulled the drive, and found about a teaspoon of water in the u-joint bellows; the water wasn't mixed with the oil/grease, but was just sitting in the bottom of the bellows. (see pic)
I also drained a bit of the gear lube from the lube drain hole on the outdrive, and compared it to some new, unused lube. The stuff I drained looks a bit lighter, but I'm not sure if it's from water or maybe if a little air was in there since I had just replaced the lube.
I have a couple of questions.
I'm thinking it looks like I need to change the bellows, yes? While I'm in there, I'll check the shift cable and replace it if it's not smooth. Does anyone think that my water could be from anything BUT a bellows leak?
I am supposed to take my daughter and a couple of her friends to our cabin, where the boat would be in the water and docked for about a week. We're leaving the last weekend in May, which doesn't give me much time to replace the bellows before then (especially since I've never done this before). What are the risks in changing the bellows AFTER our trip?
Finally, does the gear lube in the two pictures look like something to be concerned about?
Thanks for your help!