Came across this recently.

Auto trans performance parts for the 722.6 in a Dodge ( valve body and more ) They supposedly also sell a Ford 8.8 IRS center section / axles to fit Dodge.

Challenger


Flex joint to u joint conversion plates, not sure what bolt on u joint yokes they are using, does not look like Ford 4 bolt on u joint. Same link shows 6 ball "930 Porsche" CV joints being used as drive shaft joints.

The Driveshaft Shop | Driveshaft Conversion Plates - Driveshaft Conversion Parts


Page 3 shows a 4 bolt flange for the SRT-8, I think this is a 722.6 trans, anyone know if a 4 bolt flange is made on the Mercedes side of things? ( AMG something ? )

I intend to do a 8.8 conversion on a R129 at some point and a 4 bolt trans flange might make for a cleaner install. For a drive shaft I'd use one from an IRS equipped Ford Explorer / sport trac, Mercury Mountaineer. This shaft has a full diameter spline section to allow for movement but not major plunge like a live axle system. ( picture two drive shaft tubes that slide into each other and have splines formed on them.) These diffs have an aluminum housing to cut weight, limited slips / gear choices are plentiful .

This shaft might be able to eliminate the center u joint and bearing if everything lines up properly.

For axle shafts, the stock Ford tripod inner joint with a resplined Ford shaft to the MB joint will be enough ( low ish power ) . There is a chance that diff flanges with the MB bolt pattern would be a better choice if proper length stock axles can be located.

The flange is the same as the Mercedes for the 4 bolt 110mm bolt circle and the 3 bolt 110mm bolt circle. Many driveshaft shops do this now. I deal with this all the time with the 722.6 swaps in many different cars. They use a standard 1340 u joint or a cv joint. You do not need a slip joint with the cv joint because they have play in them when you do a 1 piece driveshaft but of course with a two piece they do it the same as mercedes does it.
For the diff you can drop anything you want in there with enough modification to the subframe. Axles are not really a problem until you are making around 450-500lbft of torque and launching on slicks with a stall converter.

I think your over complicating things.

Jagsthatrun.com

I'm thinking your answer is too simplistic.


whipplem104, in another post I talked about using a W202 rear sub in a R129 in order to keep wide wheels under the fenders. It looks like that won't gain enough clearance to be worth it. ( 1 1/2" )

Cutting and narrowing the R129 is a better choice. I should be able to slightly extend the stock ears or add structure to the body for mounting so this nixes the likely to be different contour / mounting W202 sub. If someone wanted to use stock axles / diff. The W202 axles would be useful.

Adding mounts for the Ford 8.8 won't be an issue. The noted company makes 8.8 conversions for Dodges that use MB parts so it won't be much of a stretch to use bits and pieces on the MB side.

The goal is to build a track day R129 that is still street legal. Rubber drive shaft / rear sub mounts / diff mounts are going to go away so moving things around is less of an issue at that point anyway.

They sell a mb 3 bolt to a 4 bolt u joint adapter.

Stealth Conversions Mercedes V8 Parts

I got one, gunna use it to bolt a fox body mustang driveshaft (302 w a t5), probably shortened, and using the stock mb diff(for now)

The mopar stuff uses the 215mm differential. I am currently putting one of those in a w124 subframe which is pretty much the same as a r129. You will have to custom weld it in. Mount locations for the rear covers are not the same. And the depth from the front mount is not the same. I also found that the standard subframe was easier than the 400-500e one to use with the larger diff and I imagine you will find the same on the 129. It will require more modifications to the front mount location for clearance.
If you are going to narrow the rear subframe anyways. I would build a jig and then narrow it and build a new subframe from tube steel with the differential you want. Most likely going to be easier than doing all that on a standard one.