Thanks guys, picked it up at the scrap yard today and looking to sell it; just needed to see what it was first.
I passed up the chance to get a couple other ingots (not this shape and not same stuff). They were quite a bit harder and not marked so I didn't buy them. They were long and heavy, one was broken and it looked like a brittle fracture, not a ductile failure like lead would give (hey, I actually used some information from my materials science class!).