I've always had a question about the M113 - were any of the -113 series made out of steel hulls? Reason I ask is that a couple years back I saw a flatbed truck heading north on I-81 with a -113 track on it, and it was covered in RUST. No paint, just rust, like it had a steel hull, the paint had been stripped off, and left outside for a while. I know the majority of them were aluminum, but I can't remember if any, even the early ones, were steel hulled.