I recently purchased a Heuer Monnin 844-4 and wonder if some of you can help me sort out a few things:

1) I am not able to open the watch at this time but wonder if someone can tell me what movement should be in the watch? My understating is an ETA 2890, but I have read it could have the ETA 2879. The watch will be serviced soon so I will find out for certain then. But I am still curious.

https://veblenist.com/blogs/watch-ar...lectors-guide:
"The Heuer Monnin was first publicly marketed in the 1979 Heuer catalogue. The first two variants of the 844s are made in France. Production then moved to Switzerland for 844-2 through 844-5, with the 844-5 being the first to feature “TAG Heuer” on the dial. The 844 series were then succeeded by the 1000 series."

2) Can anyone provide guidance as to when the Heuer Monnin 844-4 was produced? Again, there is very little written about this watch so any clarity that I can gain here would be appreciated.