Bob, Took out the kickdown switch on a 250SE 4 door. It is about 10 cm long-from s/w to two male contacts. It has about 35 mm of 20 mm threads and a lock nut on the threads. The whole thing screws into the firewall from the engine bay with the lock nut holding it tight. On the 250 -about the first 15 mm were screwed into the firewall threads and the locknut against it, leaving about 8 mm exposed. Didn't see any plastic pieces--??