The Parade of Progress came to town in the early '50s and I remember seeing the whole fleet as they entered the city and again when my parents took me down town to the display.
I was about 8 at the time and the trucks really impressed me with the way the sides folded out to create more display space. The one demonstration that I still remember was on microwaves.
The truck in the link has either been drastically modified or has had a major portion removed for rebuilding. This is what they looked like.
Google 'futureliner' and you can find the history of these magnificent machines and several articles showing the rebuilding processes.