I have an introduction thread in the od forum that I outlined my ambitious build plans but I need some recommendations to finalize my mental picture.

I need some rear suspension/driveline recommendations for a w124 to handle a potential ludicrous amount of power. I'm trying to decide on driveshaft and complete rear suspension from a V8 w124 or 600SL. Will the w124 stuff hold or would the SL axle assembly be needed? I will be swapping in a different ring and pinion and Quaife LSD as well. I sorta hope I can get away with the V8 stuff because it's easier to obtain but won't have any problem with kicking up the 600 stuff

Time isn't an issue with this either. I will be obtaining parts and building the entire assembly in my garage as time and money allow then swap the whole thing over a weekend. Any feedback is welcome. Take your best shot

Well it depends on what you mean by ludicrous amount of power. The standard e320 diff is the same size as the v8 one just a different subframe. If you have an older 300e then it will have a smaller diff. Axles are really only a problem if you put slicks on it and try to launch hard. Then the stubs are the breaking point in the diff or in the hub. Then you are on a completely custom setup track. Your 1st weakness is the driveshaft. FLex joints and center support and center ujoint.

Car is a '93 300D, I'm pretty sure that is all the tiny stuff. My ambitious plan is a bananas om606 swap. It will see the occasional gratuitous smoky burnout and more rarely a stoplight race but won't be hardcore launched on slicks. And if I ever do that I know that I'll deserve what carnage I cause.

Will the driveshaft assembly or axle shafts from a V12 129 or 140 hold up do you think? Or what about newer AMG V8 kompressor stuff but modified to fit? Just kind of tossing ideas out right now...

I would like to use off-the-shelf factory components wherever possible or some modified factory stuff. Custom fabbed stuff is a last resort but I also understand I may be blazing a few trails

To deal with ludicrous engine power:

1) Obtain a ludicrous gearbox,
2) Obtain a ludicrous driveline,
3) Obtain a ludicrous ring & pinion set,
4) Obtain ludicrous axles,
5) Obtain ludicrous wheels,
6) Obtain ludicrous tires.

There, wasn't that easy? And the sound slumber of not so much as even one number was disturbed, nor was it necessary to give consideration to the least amount of engineering.

Stoopid me, this is all I have to do

One of my posts disappeared...

Ludicrous power means at least 500rwhp and 650ish tq. That's approximately what a stock long block om606 will handle. And I want to do significantly more work to the long block. See my "yo, new member" thread in od for more specifics, there's quite an ambitious list.

It's a '93 300D so I think it's got the tiny stuff. I won't be launching from slicks off of a rev limiter but I will be doing an occasional gratuitous smoky burnout and a less frequent stoplight race. I may need to use drag radials though to hook up a little. I'll at least know that I deserve what I get if I do anything too dumb

I'm going to use a 722.6 so the driveshaft from a kompressor or biturbo car could potentially be used. I'd imagine that could handle a pretty decent amount of power. Would a v12 140 differential and axle shafts handle a bunch of power and be not too much of a pain to retrofit? Or even a kompressor or biturbo rear axle assembly? I'm just throwing ideas out now

Off-the-shelf factory parts are my first priority, then modified factory parts. I would like to stay away from full custom setups but I understand I may need to go that route

So. the standard 210mm diff from a e320 will handle the torque. If you want the v8 subframe it has a better rear mount for the differential but the diffs are the same size. Just a different rear cover for the subframe. The axles will handle street tires just fine and until you are trying for sub 1.7-1.6 60' in the 1.4 mile you are fine. As far as the driveshaft just get a custom one made it is cheaper and better than buying a factory driveshaft and having it modified. You eliminate the flex discs and put an aluminum adapter to a 1340 u-joint. Axles there are really no upgrades unless you really get into the custome world. I have a thread on some of this stuff here. I am doing a 215mm diff with a lot of factory parts but also a lot of custom machining and a widened track to accommodate the axles. But I am going to launch hard at the drag strip.

Awesome, thanks for the feedback. This is actually better news than I had hoped to hear. I'll probably source V8 stuff, maybe 500SL, it should be easier to find than V12 stuff.

Do drag radials fall into the street tire category? I really don't think I'll be subjecting the driveline to the kind of shock that drag racing produces, definitely not on a consistent basis

I can tell you that the sl subframes have different part numbers even though they look the same. I have never measured one or tried to install one. If you are going to switch subframes then just source a 400e one. There are no differences in axle strength but there are differences in length.
Like I said if you are not trying to cut low 60' times then you are fine. Besides unless you put a supercharger on the car you are not going to have that much tq from a stop. If you are doing burn outs all the time and have wheel hop then it really does not matter much what you have and it will break.

SL stuff should fit, the 129 is based on the 124 just shorter. The difference looks like in the way they are put together, so parts may not be able to be mixed and matched just a whole assembly swap.