and not rare.
The fiat is ref GP 49480, solid case back. 3 register. Lacquered hands. Different movement. Etc etc Many differences. 

Pics from internet
The Fiat was made for Fiat workers as a long working reward. Several can be found quite easily for sale. I don’t have exact production numbers but many seem to have been made.
My Abarth was exclusively commissioned by an Abarth car collector group is Japan in 2004 and only 50 pieces made.
🤝