Hi Guys....Happy New Year to one and all.
My 300SL uses the infamous 722.5 Auto Transmission with the 5th gear ( some call it the back gear ). How can I tell if this 5th gear is kicking in? Can it be checked by using the RPM vs SPEED? At the moment the RPM is 2500 at a speed of 110km/hr on a flat straight road. Is this about right with the 5th gear engaged? Any way to check? Cheers.

 

Your 5th gear works. You can demonstrate this to yourself by driving at speed and moving the shift lever from "D" to "4", as when you do this the tranny will downshift from 5th to 4th and the revs will jump.