I can add other data sensors and send their NMEA information to the repeater, which shows up to two different data types at a time. We haven't bothered. Great, well proven devices with a long track record and many thousands of existing installations world-wide. Ours were new in 1989. They are no longer in production.
Parts are easy to find.
Pay close attention to the condition of the exhaust risers. Tune the engines regularly. Change the water pump impellers annually. These old gauges do not show numbers, just white lines. With TLC we expect this drive train to last a long time.