I do several of the "Targa" tours with this w123, lowered, bilsteins, etc. Noticed significant roll in rear on the twisties. Installed this bar this week and now we no longer lift the hind leg in the corners. Made a significant difference. Just info..

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The 123 comes with a rear bar....is this one different or was your car missing one?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I'm assuming OP is referring to the thicker, custom sway bar that Greazzer developed.

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1981 240D 4sp manual. Ivory White.

Indeed Shern.
I was exploring custom made larger front and rear bars but very pricey. Then John from Huntington Beach alerted me to Mark (whom I have previously dealt with) and the 15.88 mm ready to go bar. It came with poly bushings and grease fittings. I recommend using Allen cap screw bolts instead of the six external flat bolts for ease of installation.
Before any flaming, I agree the w123 is one of the most enjoyable and forgiving cars to drive. Perfect balance of comfort and handling.
This bar is not for a stock factory car. If you have 16" tires and understand chassis dynamics will be altered then this is a good option for you. It was for my application.