Okay, I did this job yesterday. Here's what I found:
The bushings on the 500E are both external: one at the base of the selector lever where it comes through the floorpan, and one on the lever that hooks over the rotating tang on the side of the trans body. The two are linked by a long removable rod, which is what the bushings are intended to cushion.
(I can't rule out that there might be a bushing in the interior console, as Jerry points out, but it wasn't necessary on this car.)
In this case, the rear (selector) bushing was completely gone. Front one was in pretty good condition, but I figured I ought to leverage the time investment in working underneath, as the parts are so inexpensive.
I found the notes in this post valuable:
Sloppy 93 W124 shift linkage?
Yes, it's pretty hard to work on, due to space. Tight quarters both front and rear. Having the car on a lift would have made this enormously easier. I did it on ramps in the driveway. No room for a creeper, so there was a lot of flipped-turtle squirming in and out from under. I recommend having a helper nearby to fetch forgotten or necessary items. I didn't have one and it slowed me down.
If working on ramps, exercise all safety precautions! The transmission goes into neutral, so you lose the small safeguard of the parking pin. I put an extra pair of ramps in as safety stands, locked both parking and foot brakes, and placed another car in back to avoid rolloff. Having a 500E come down on your chest would be a bad day.
A bright LED headlamp is an enormous aid. It's bloody well dark under a car. However, don't be a doofus like I was, and don't buy a unit where the battery pack is carried at the back of your head (where your increasingly sore skull will be resting on it).
Get one with batteries on the sides, and no clips or buckles in back. Your head will thank you a few hours later! You'll also want some clear safety glasses to keep crud from falling in your eyes.
In the rear, as noted, you'll want to put the selector in neutral. And block it off -- if your manipulations push the selector tang toward the back of the car, the actual console shifter will go *forward*, and can lock into Park, which will entail squirming out from under the car to fix. Don't ask me how I found this out.
The rod is held on to the selector lever by a clip. Easy to pop off with a long screwdriver. The clip was roadworn a bit, and so I replaced it preventatively. Two or three bucks, as I recall.
Once the clip is off, the rod comes off trivially. You'll want the rod OUT before you do the rear bushing, which is done in place. Every bit of obstruction makes that job harder. I attempted it originally with the rod in. No way.
Go to the front and remove the lever that connects to the external tab from the trans. This has a 10mm doubleheaded bolt (with washer, don't lose it). Extract the bolt, put it in your safe inventory area, and then pry the lever off of the tab. It's a heavy J shape which comes off straight to the side. Took me a few minutes to figure that out.
Once you've got that, the rod-and-J-lever assembly should slide out to the front. REMEMBER TO RECORD THE CORRECT ORIENTATION! It *will* go back together and back in to the car in an unfastenable mirrored orientation. Normally I take notes on this stuff, but I was rattled at this point and forgot.
Definitely do the front bushing on the bench. You'll want to remove the rod first. It's held in place by a clip identical to the one at the rear. This one was in good shape and clean, unlike the rear one, so I re-used it.
On mine, the original front bushing was good enough that it had to be cut out with a utility blade. I tried a few ways to squeeze the new bushing in experimentally, all of which didn't look very promising.
What I did was to go find a 7mm bolt and nut, two big washers, and a squat wide socket (18mm?). The socket is to give the bushing space to pop into on the far side as things tighten.
Assemble the stack with bolt, washer, bushing, J-lever, socket, washer, nut, and tighten until the bushing is in place. I used a light durable grease all over the bushing. This squeezed out alarmingly: those bushings are a tight fit.
Once the rod-and-J-lever combination is out, doing the work is really easy. Under two minutes.
Back under the car, the selector lever bushing has to be done in place. This is a tough one. Deep narrow space, partly occluded by the exhaust. I have seen long pliers recommended, but I worked
with standard-length needlenoses. Longer ones might have made it fractionally easier.
I first tried a washer stack without the socket. Also needed to go get a shorter bolt, 40mm. Nothing longer will fit. The socketless washer stack idea failed. The bushing really needs open space to pop into as it goes through the lever opening.
Went out and bought a couple of 3/4-inch inside diameter washers. I put two of them into the stack, so I had bolt-smallwasher-bushing-lever-twobigwashers-smallwasher-nut, again with some light grease. Assembling this stack with the lever attached to the car, in the small space available, is a bear. But once done, and tightened, the bushing was perfectly in place.
I don't have one of those "squeeze wrench" gizmos advertised on late night TV, and don't know if they're any good, but I can tell you that doing this tightening with a standard wrench is slow and annoying. Not a lot of radial space. This would be a good test for an SW.
Clean everything and slide the rod-and-J-lever assembly back in from the front. You did record the orientation when you took it out, right?
Fasten the front first. The J-lever is actually quite difficult to put back on the tang that comes out of the trans. And you want it firmly seated!
Also be sure that the switch behind the trans tang (a little arm about 1.5cm high that rotates concentrically and independently with the tang) mates to the J-lever. There's a small hole in the lever and a little tab in the switch arm which has to go into that hole. The little arm is the neutral safety switch, right?
The tang is rectangular and there are two rectangular ports aligned in the lever body at the curve of the J. I had to use one hand to apply side pressure, while the other hand reached back and grabbed the selector rod at the back, and moved the mechanism back and forth. Some assembly lube is also recommended.
The doubleheaded bolt is a good check that the J-lever is firmly in place. It won't go through until the clip seats properly. Remember the washer on reassembly. I can't recall the torque spec now, but tighten it prudently. You wouldn't want this coming off without warning.
The rod should easily re-mate with the new bushing at the rear with only finger pressure. I picked up the clip and seated it against the mount point with needlenoses, then gently snapped it in with fingertips. Rotate 360 to confirm it's solidly on.
Test drive carefully, remembering to remove your safety stands and other measures before coming off the ramps. (Once, many years ago, I forgot this. Very red face.)
In this case, the new bushings make the trans feel factory new. Previously there had been excessive lightness of action and a bit of slop to the selector lever. Now it's firm and precise, feels as a Benz is supposed to feel.
The initial symptom of bushing trouble had been an annoying buzz at high (very high) speeds or hard acceleration. That is completely gone. The car interior actually seems quieter when even not in that regime, so the shifter may have been transmitting subaudible vibration, coming from the loose point at the back where the bushing was AWOL.
Is this a good thing to have done on your MB? If your car needs it, yes, absolutely. I had no trouble but someone else has noted that bushing failure can result in trans trouble. The selector could get into an intermediate state, they say, and damage the valve body. But it's worth it just for feel and sound issues.
Here's the cost upshot. Components are trivially cheap. Under ten bucks for two bushings and two clips. Plus a buck or two worth of bolts and washers for the squeeze job.
But I called Autobahn Motors for a quote on just this job, F and R bushings, and their service adviser instantly said, "$225, sir."
Geez. How do people *own* these vehicles for the long term and have to pay dealer shop rates? Absolutely extortionate.
It took me about three hours to do this job, exclusive of going to buy washers and the like. If I'd had more accurate and detailed instructions, such as these will hopefully be, I'd have had it over in maybe 60-90 minutes.
Now that I've done it once, I could get it in 30 to 45 minutes. If I were a pro wrench with a lift and every tool going, maybe 15 minutes. Frankly, a lot of the time was spent just figuring stuff out. I hope that this saves others some time and trouble.