Many times confused to 15tee, which is not same model as TTL. The TTL is a more sophisticated version, but unfortunately too expensive to sell.
Metering is now more fast and accurate, thanks to one wider EV-range.
Manufactured propably only in 1980 and around 10.000 units?
Known serials:
80-5047- napchop
80-5179
80-5285 - napchop
80-9176
80-9226
8007041 - Vlad