does anyone know if the auto boxes are the same on 6 cyl and v8 w126's? or will it fit behind the v8 3.8.

No, they have different bellhousings

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MERCEDES Benz Master Guild Technician (6 TIMES)
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can i swap bell housings?

You would need depth guage & shims to set the axial bearing clearance on the K1 clutch drum...also the kickdown cable would have to be swapped...the driveshaft output flange....OF course the trans wouldn't shift correctly as the design of the valve body & governor is completely different for a 6 cyl VS a 8 cyl.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator