Only works if your current transmission has a red modulator. Will also work on some late W123 240's. Complete with the cap as shown. To get this to work right you MUST understand how the vacuum system works on those models. It is VERY FINICKY!. SEE MY manual below
No longer available new - super hard to find and a must for shifting of these transmissions!
1980 and 1981 NON Turbo 300D, 300CD Transmission Red Modulator - USED