Here's a couple of links from past threads with pictures from the I-80 Truck Museum in Walcott, IA.
http://www.expeditersonline.com/forum/layover-lounge/53289-iowa-80-trucking-museum.html
http://www.expeditersonline.com/forum/general-expediter-forum/53281-iowa-80-truck-museum.html
And nary a wheel chock can be seen!