they look like what they use to call "moon boots" because the sole pattern was like that om the moon i suppose lol
Try modifying your search to include vintage "muck boots". I've seen similar tread patterns on even current boots, and the way the sole gradually wraps up instead of ending at a sharp 90 before coming up to meet the bottom of the boot is very popular in this style of boot as well. Maybe places like Cabela's or another outdoor fitter like Academy Sports or Dicks may carry similar.
I understand it was a very recognizable picture, trust me. I searched everywhere and have asked everyone who has had their hands on the original suit with no help. I was hoping to get a different perspective on it by only showing the part that matters.