Here's a Steube style chassis I built a few years back and never used:
Not a replica of anything, this would be good for the first race, which was held in January. It has a motorbox and as you can see is configured for a Cox guide.
By January 1969 the low profile Jet Flag was becoming popular, along with the half-rail (no motorbox) center section. While both the Cox guide and the motorbox design held on for a little while longer, they were on their way out.
This chassis needs some cleaning and detail work, but should work just fine. Now, I need a Steube style motor...