I just upgraded my wagon with first generation w126 rotors and calipers. I used a 1985 300SD to search for parts.

The only difference between w123 and 1st gen. w126 brakes is the front rotors are vented and thicker on the w126 and I think the caliper has a shorter piston. The rear calipers and rotors are exactly the same.

This upgrade is only for the benefit of the vented rotors and no different than a caliper and rotor R&R. I replaced the hoses and my front wheel bearings at the same time. There is no additional stopping power ... just more time to use it.

I used this write-up to help me. Thanks rhodes2010, it was helpful:
How To Replace Front Rotor W123


Before:


After:

__________________
Chad
2013 Jeep Unlimited Rubicon
OBK#44
"Pleasure in the job puts perfection in the work." - Aristotle (384-322 B.C.)

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1985 300TD - Red Dragon
1986 300SDL - Coda
1991 - 300TE
1995 - E320
1985 300CD - Gladys
2006 Nissan Pathfinder LE
1998 Acura 3.0 CL