@ crazykongfan - I don't believe the overlay is Willis. Their pac overlays are pretty standard and that one appears to be a bootleg made to duplicate the look and feel of the original.
@ oldtymetoys - the blue one is the Willis Time Pilot cpo, it says right on the front. the darker one you have is likely a bootleg. I have one or two just like it in my stash and once I get to it I'll do a write up.
@ cleverlyj - willis made SI and SI deluxe, but the cpo's are not metal. There are a handful of bootleg metal cpo's floating around
Just because an overlay isn't the original dedicated overlay that doesn't instantly mean its Willis. They were a legit company and put identification right on their stuff (unless someone has documentation to prove me wrong!) The artwork they did was almost NEVER reflective of the original design, I would guess due to licensing issues. There are a few exceptions, Tron being one.
Bootleg's were rampant during the boom, ops didn't want to pay to buy OEM parts when they could have Joe artist at the print shop run off a few for a fraction of the price. When you have a huge route and 50 pacs or ms pacs on location, it pays to bootleg.