Yes, please ask more questions.
Odds are they would have been assembly mules of varying body styles to make sure the assembly process worked.
Correct on both engines Don.
Below are Chevrolet internal documents reflecting the the 50 Z-11 complete engines built and 20 short blocks built. The number of heads, etc are unknown.
The Mystery Motor is incredibly small.
I know it was far less than 50, more like 30 plus several sets of heads, etc.
I met a man that was in Daytona when the engines were shipped to Smokey Yunick and Ray Fox.
While Chevrolet claimed 50 to NASCAR those 2 guys would ship engines back and forth between their shops when NASCAR came to count to get to 50. The guy I met said it was 29 engines.
Chevrolet even had a couple of cars pulled out of Dealer inventory and used for the Mystery Motor, Smokey’s black and gold car and Juniors SS car. I believe the red test car was shipped to the Az proving from Mich. not sure exactly but does not matter.
So, given the small number produced in total of both engines, I find it hard to believe that’s what they were doing with those cars.