They made both. The most stick and aluminum construction came after they stopped making the "rubber" trailer. When I was contemplating buying one and wanted to see them built, they gave me a guided tour of the plant and the foreman showed me the little trailer. He said they no longer built them. I saw one shortly after in Reseda California in 1969, but have never seen any others since then. The problem with the site you gave me the link is not enough knowledge. My
Quantum 5 is a perfect example as I know well, where and when they were built. Harold