Performance, I actually had not considered that..........I did a quick grind test and I think you might be right on it being cast iron. When I put the grinder to the base of the HF jack it produced yellow/orangeish sparks but when I grinded on some home depot steel next to me I got a very similar color but just a lot more spark.........and from my quick research this seems consistent with the grind tests of cast iron vs. steel.

I suppose I should grind down the old welds and go back with a nickel N99 rod? Some posts mention stainless steel er308 works well also?