I think they all slosh fluid out and if that can happen, they can absorb moisture from the air to form corrosives, unless you use silicone DOT 5 like me. It is also a great paint remover - why most cars you see in the junkyard have a rusted firewall around the MC. If it tires you and you don't like rusty cast-iron, see my post where I used a 95-95 Breeze ABS MC in my 64 Valiant, on a 4 to 2-bolt adapter plate ($30 ebay). The pedal wound up in the same place. Also works on a booster (my 65 Newport). Many other 2-bolt alum MC's can work. Dr Diff sells one w/ plate for ~$120, similar to 1980's Dodge one but offers a smaller bore (for easier pedal).
