The right rear trailing arm on my '83 300SD has an almost rusted-thru lower shock mount, so time to replace the arm.

After checking part numbers, it looks as though the rear trailing arms for the 123's are the same as the 126's. Is this correct? I imagine other things like bearings, rotors, etc. may not be the same, but I haven't checked yet.

I have a buddy who may part out a '77 240D, so I'm wondering if the arms are the same.

Thanks