How do you go about changing the bellows for the exhaust and drive shaft on a MerCruiser 5.7 Alpha One?

This is not an extreemly difficult thing to do, but you will need some special tools. You have to remove the drive which is quite heavy. You should change the drive oil, water pump impeller, and lubricate the gimbal bearing while you are there. Also do a pressure test to check for leaking seals. I would suggest investing in a shop manual.

As you have to remove the drive, I would suggest changing the shift cable and bellows and trim and limit senders, and the water hose also