[dmjlambert]

I wouldn't have any ideas on chasing that with an LS engine. On a first generation stock engine there's really no electric going to the engine that could leak except the coil and spark plugs. But I would start by removing the ground wire on the radiator and anode and see if you can get that same .2 V reading, and check out that sacrificial anode condition. I think if it isn't corroding, it's not doing its job and you might as well just not have it. What kind of coolant do you have, is it plain green stuff, ethylene glycol with corrosion inhibitors? Or something else? Do you change it every year or two? The corrosion inhibitors supposedly wear out causing the need to replace it.