1969 Barracuda Fastback

I suggest running a ground strap to the radiator. Engine coolant has a side effect of acting as an electrolyte. That fact contributes to the pitting you see in the aluminum thermostat housing on lots of engines. Isolating the radiator from ground, especially since there is a dramatic temperature change happening inside can cause a higher voltage build-up in the coolant. At worst, it won't hurt.