Mystery Numbers Solved!

Thanks to Larry Fritzen, the exact nature of these numbers has been deciphered! He found the build sheets of 3 cars that were on the assembly line together on March 28, 1977.
 
The first one is a rare yellow 1977 Trans Am. The VIN sequence is 185491, and the penciled number is 9824.

The second car, also yellow, is a Camaro Z28. The penciled number here is 9825.

The final car, the one the sheets were stuffed into, is an even more rare 403-powered Y82 with California emissions. On this car, the VIN sequence is 185492 and the penciled number is 9826.

It is apparent these 3 cars were consecutive on the assembly line. The Trans Am VIN sequence numbers are concurrent. The Camaro is apparently between them, since its penciled number is between the numbers of the Trans Ams. The assembly line worker missed hiding the build sheets in a couple of cars and then triple-stuffed the third car, which Larry later owned.
 
Based on this, it appears the number was an easier way to keep the build sheets in order on the assembly line. This might mean that the big 4-digit number was chalked on the car body (it would have been nice) but I have never found one. John Limes told me that he did find that on his excellent 1977 403-powered Trans Am.

Below, here are a couple more These two were found in one car. These are harder to read, but you can still see that one is a Camaro and one is a Y82. Note the "Akron Tires" note on the Camaro, which was going to a dealer in the Akron area.