What's the best way to prevent this condition. If I remember correctly you have to install a cathode into the coolant system? Any help or thoughts are appreciated.

You used to be able to buy radiator caps with a zinc anode built in, or possibly just google something like "sacrificial zinc anode" and see what comes up. I'll bet Summit, Jeg's and ebay all sell them.

http://www.boatzincs.com/engine.html

got mine hear and replaced one of the block plugs. had to trim it down to fit.

the rad cap one might be easier.

I got one off of Ebay that goes where the petcock is.

I put one of the petcock ones in my 451 build 6 yrs ago and took it out to check it 6 months ago and it had not visibly changed.

I bought the radiator cap off eBay, wasn't cheap though...15 bucks with 10 bucks shipping coming from 4 cities over...I put it directly into my radiator. I have Zinc Anodes that I purchased from BoatZincs.com but I have yet to install one of them because I haven't made the switch yet to my Aluminum WP housing/pump. I honestly haven't checked it since I installed it a year ago, I hope it's doing something. Then I again, I hope I don't have any issues. I think the number I got was RC-33

I bought a zinc for the cap on my Challey and after 4 years it looks the same but the coolant was dirty . I guess I didn't have any electrolysis.

..i read somewhere to take a voltage reading between your positive battery terminal and your coolant with your rad cap off and system under load (lights on etc.)
you don't want to read more than .1 volts.
if you have an aluminum rad don't use the ground from your neg terminal to the rad.
i have not tried this myself.