Mine is a cut-down 1939 Westinghouse Jr. Ice, it has non-slip feet and a single bolt going through the bed to prevent theft and facilitate removal if needed. The bolt has a large rubber grommet on the inside so it does not leak water from melting ice (these coolers have an internal drain in the corner).
https://www.flickr.com/photos/advance-design_parts_co/48374593956/in/album-72157631866985745/