From my parts reference, the furthest to the left is the "Temperature Sensor, Temperature Switch to Cylinder Head, 130 Grad". The middle one is the "Sender Unit, Water Temperature Gauge". The part with the two plugs going into is the "Sender Unit, Continuous Injection System."
1988 560SL Black/Palomino
1988 300SEL Black Pearl/Burgandy
1984 500SEC Anthracite Grey/Palomino