A few w140 questions.
 

Relating to a 1996 S320;

Someone said the raidio antenna is located in the bumper and the antenna that rises from the rear fender is actually for the factory installed phone. Is this correct?

I believe the shifter indicates that there is a seperate gate or at least some kind of switch to go between 4 and D but I don't feel a click nor any change in engine rpms. What is the function of the place marked 4<>D?

your radio antenna is in the rear window.your car is the first year with the 5 speed tranny.D is all 5 gears and 4 will not allow you to get into 5th gear

so if the gear selector will not hold in the D position there is something wrong and I can not access 5th gear? any idea what may be wrong with the selector?

All W140 6-cylinder cars had a 5-speed auto. 722.5 from '92-'mod '96, and the 722.6 after that.

Radio Antenna
 

My 1995 S350 antenna is located in the rear bumper and the antenna on the quarter panel does not come up unless I turn the phone on. My 1996 S420 antenna comes up with both the phone and radio. Strange? Also, do some reading on the transmission service on your 1996 because it takes a special fluid that can only be purchased at MB. This trans is a five speed electronic shift. Always leave the S/W switch in the summer mode as if in winter mode the trans will start the car off in 2nd gear. My MB tech says it's bad on the trans. Your car also does not have a dip stick, this has to be checked by a MB tech only. MB says change fluid every 100K, however, I do mine every 30K and I have 134K now with no problems. Good Luck!

gear selector will not hold in the D position
 

The bushing in the gear selector needs to be replaced.

I thought leaving the trans switch on the 722.6 in 'W' mode made no difference in regard to transmission wear. What was your mechanic's rationale for leaving the switch in 'S'? On the newer MBs, the same switch is labeled 'S' and 'C', with the C standing for 'Comfort' mode.

trans switch
 

Sorry, I did not question him, just did what he said. :)

so, if the selector does not stay in the both horizontal postions on the 4<>D gate, I should replace a bushing?

yes you should

The mechanic left a message on my answering mach. today saying something about a shifter box (the message was garbled and I could not understand what, wexactly he said) and it costing $400 to fix. Does that make any sense?
I road tested it today and am not getting 5th gear.

There is a microswitch on the passenger side of the shifter box that can be replaced/tested once the wood is removed, If the switch is bad,(check at speeds above 45 to see if it shifts) then replace.

Have you checked the vacuum line from under the plastic cover in front of the driver's side firewall to the transmission? Do a very thorough check as this is a really cheap fix. Don't ask me how I know.

Tim