I just did this work to a gen 2, I believe the bellows are the same.
Have a mount for your stern drive ready. I found that a 6x6 with 2x4 on each side was perfect width for hanging the drive. The 2x4s were 19 inches high.
If you are going to remove the hinge pin and gimble ring, break torque on the pins while drive is mounted. I didn't remove the gimbal ring and had no access problems.
Plan the order of replacement. I did the gimbal bellows first, then exhaust, then shift bellows. You will be working mostly from below so going top down is good.
String trimmer cord is a good fish wire for the lower shift cable.
When tightening the lower shift cable, remember the whole cable turns with the nut.
The gimbal bellows inner ring needs to be pressed in,not hammered.
I stretched the exhaust bellows prior to installing it. I used spray paint can tops in each end. Tie top end off and have enough weight on bottom to stretch bellows to 8 inches or so.
Only special tool I needed was a 1x1 stick with a fender washer on the end.
Let us know your questions.
2006 Bayliner BR205
A1 Gen 2 1.47
5.0 carb engine