The system with the case serial numbers at Heuer is very simple. There are no specific Autavia, Carrera, etc. serial numbers, only Heuer serial numbers for all models. The cases of all models were consecutively numbered according to the production time of the case, no matter which model. However, sometimes 1000 Autavia cases were produced sequentially, then 500 Carrera sases, then 200 Dato-Compax cases, etc., so as not to change production at every single watch.
These serial numbers have nothing directly to do with the production time, or the assembly of the watchs, but only with the production time of the case. Sometimes watches were not assembled until years later in older cases from the stock. This explains the irregularities of the watches, case 1st series, dial 2nd series, etc.

The cases of the 1. edition Autavias were produced in 1946 for screw back Tri-Compaxes or Dato-Compaxes, but they coult not be sold in such big quantity direct after the world war, so they were in the stock over years, and Heuer used them later for the 1. edition of Autavias.