The 722.5 is like 4" longer than the 722.6. The 722.3 is nearly a direct swap. Just redrill the cross member and shift linkage for the .6 later. And you do not need a custom driveshaft or import parts from Europe.
And yes. The factory computers all need to get info from other computers. Even ABS wheel speed is required. Just a simple run engine early 90s stuff is at least HFM, EA,CC, ISC module and wiring those up and get them to work with current ABS system.
IF you want an Me computer with 722.6. Then you need the factory Traction computer and tcu from the same donor or like. And speed sensors set up etc. etc. etc. Then correct gear ratios. Tone rings for said sensors. And a bit more I imagine.

Ok good point about the 722.3. I might just do that for now.

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Current:
'74 450SLC
'89 190E
'95 E420

Previous:
'94 E320
'87 300E
'73 350SL
'75 450SL
'95 C36
'99 C43 55 swap

The .5 hydraulic shift 5 speed was only found on the ~ 90 to 93 ish 300SL / 300CE so it isn't very common.

The early 90's stuff is too fiddly / wearing out by now I would not use it.


The 97 C280 / E320 / SL320 and 97 - 99 S320 ME 2.0 / 2.1 is pretty straightforward, the rear end gear ratio is a non issue for what he is doing. ( * see bottom )

Our guy would need:

All the engine mounted stuff for ME ( a few parts are same as HFM )

ME engine harness.

ME ECM , DAS X box , key ( all of this _must_ be from same VIN )

Antenna ring around ignition sw for key, TCU , ABS / ASR computer only, no pump is needed ( these parts can be from a different VIN but generally must be same model. Some cars have ASR which amounts to a 4 channel ABS rather than 3 and some different programming )

Throttle pedal sensor. These are drive by wire, fortunately the throttle sensor is still operated be a cable under the hood making a conversion easy.

722.6 trans with an internal gear ratio that matches the TCU ratio.

Gear shifter that matches the TCU type. (need for EGS51 P R N D 4 3 2 1, not EGS52 P R N D - + )

Aftermarket electronic speedometer fooler.

*
As I see it, only input from the "car" this conversion needs is wheel speed.

Wheel speed is fed into the ABS / ASR computer then it talks to the ECM and TCU over a CAN bus. An electronic speedometer fooler is all that one needs to correct for a different rear end ratio. You might be able to tap into the existing wheel speed sensor but a 2nd speed sensor mounted to the existing tone wheel would keep both systems separate.

I'm reasonably sure that the instrument cluster isn't involved in any ABS / ECM / TCU communication.

The ABS / ASR will fault out if it doesn't see all of the wheel speeds, I'm reasonably sure that if one rear wheel speed sensor is operational, it won't put the trans into limp. Even if it did, providing signal to the other inputs would not be an issue to solve this problem.

As for the cars original ABS, I'd think it would still work but I don't know enough about that system to say for sure.

That's about the way my car is setup. But sourcing parts from multiple cars is risky. If something goes wrong you wont know if its a part incompatibility or not. Also I don't this his 96 has a chip in the key my 96 SL600 did not. But the key taped to the antenna thing is my planed way out for my next build.

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John Roncallo