Full Monte said:
Yes, it is a 4-speed tranny. If memory serves, I'm doing about 2500 rpm at 65. Will need to check when I can get the car away from the wife. I'm not going to convert to an overdrive unit anytime soon, if at all.
If it's running 2500 RPM at 65 for sure, I wouldn't worry about it...you're pretty close to ideal already. Getting the RPM's too much lower would likely do as much harm as good...these engines like to rev higher than we're used to
(the governor's set somewhere above 4500 RPM, and these engines were made to run right at the governor all day long)...
If I put in the 5-speed, that might be cool. It would likely cob up the wooden plate around the gear selector, but not a big deal (except to the wife).
If you were able to find a 300E 5 speed, you might be able to steal the plate from that car...or, the plate that's on there now could be adapted. I know that the 123 center console trim was the same with an auto or a 4 speed, except that the shift boot attaches to the trim (and, also, that many 4 speed 123's had manual windows, so no spaces for the switches in the trim). But, again, I think the biggest obstacle would be actually finding the tranny...personally, I would wait to swap it unless and until the auto dies.
Warden, you certainly throw the technical details around...you must have been around MBZ cars a lot.
Some of what I know has come from direct experience...I've had my car for a bit over 3 years now and have done a reasonable amount of work on her. But, I have to give credit where it's due...I was part of a different website for a long time that is set up similar to this one but is strictly for M-B's. The diesel forum there was very active, and between having questions myself and reading other posts, I was able to learn quite a bit. But, of course, as they say, I'm still learning, as we all are.
I only left that site because I didn't care for the changing climate...it was getting to the point where questions were only answered by someone yelling (sometimes quite rudely) at the thread starter to "do a search".
When I was younger, I spent a fair amount of time on the side of various highways (notably the I-5), which did two things for me. First, it permanently turned me off to gasoline engines...second, it led me to make a strong effort to learn as much about the vehicles I owned (or was about to buy) as I possibly could. The irony there is, I've only needed this in an urgent situation once...my diesels have been so much more reliable that I've only been stranded three times since then (over the course of about 6 years now, which is a vast improvement on being stranded monthly!)...once when the battery terminal at the starter broke on my old van, once when the injector pump died on my truck, and once when the voltage regulator/contact brush assembly went out on the Benz (and then, all I needed was a jumpstart, and then drove the rest of the way to L.A.
).
So, I consider myself to have a reasonable knowledge on these cars, but I wouldn't call myself a guru by any means...while, to the best of my knowledge, everything I've said is accurate, as much of it is data gathered from other people as it is information I've acquired firsthand. But, IMHO, that's the way it is on these sites...people are able to learn things, and once they have learned this, they can then help others.