Magnesium Anode Cone 2000 bravo 3
 

I have a 2000 2800scr in fresh water with Magnesium Anodes - that really work well. Question please and thanks:
Given that new drives have an anode cone, is it possibly to install one on an older prop shaft?
Also,
I have one broken stainless wire leading from the bell housing to the drive. My mechanic mentioned that it is not necessary - is this advise correct?

Yes

To my knowledge YES, he is correct, this wire isn't completely necessary.

Thanks shrew. The earlier bravo 3’s are known for corrosion problems and I wish to mitigate it on my drive as much as possible.

Being that you boat in fresh water you can probably get away with the broken bonding wire but when it's time to service the bellows I would replace it. If you boated in salty water it's a must fix IMO.

Note while the water is fresh doesn't mean its ph is neutral.

Later Bravo III's are equally susceptible. The only difference with the later models is they added a second anode underneath the anti-ventilation plate and added a prop shaft anode (cone).

Thanks Shrew.
I’ve been standing on ice prepping the lifted boat for launch in 4 weeks (heading to Canada’s most beautiful province of Florida in the mean time). I noticed a little threaded hole in the end of the prop shaft - and just wondered if it would accommodate an anode cone? I’m diligent with refreshing the anodes - despite the fact I’m still getting some corrosion

Is the aluminum of the outdrive casing corroding? Or are the zinc's corroding?

The most common location for drive corrosion is along the thin spots, like the edge of the anti-ventilation plate and the skeg.

Zinc's are supposed to corrode. If they corrode beyond 50%, I change them. You might simply have a higher change rate than normal. If that is the case and you are in freshwater, then I would be looking for stray current at the dock.

Is this boat stored in the water or on land?

Bravo 3’s commonly corroded at the back of the bullet due to the stainless steel props interacting with the aluminum.