Beltline chrome is the narrow chrome channel pieces which are located about 3 feet above the ground, midway up a 220S, on the front and rear fenders, and a curving piece on the rear doors. If you were to (don't try this) drive the car into water about 3 feet deep, the beltline chrome would be at the waterline.
But seriously folks, I'm afraid there is no shortcut to removing the beltline chrome pieces on your 220S. The narrow "rat tail" chrome strips are held in place by T shaped studs and nuts, only accessible from the inside of the sheet metal. In addition, the rat tails on the rear fenders have two twisted tangs at the pointed end. These tangs are twisted approx. 45 degrees. They need to be straightened before the rattail can be removed from the fender. Carefully straighten from the inside with a pair of pliers or vice grips.
To remove the T-shaped studs, what I do follows: From the inside, spray all of the T-shaped fasteners and nuts you wish to remove with the penetrating Oil of your choice. (Liquid Wrench or similar.) Let stand for at least a few hours. To avoid scratching the chrome, wrap some electrical tape around the jaws of a wide pair of vice grips. Locate the T-fastener you wish to remove. Adjust the vice grips locked position open so that they will hold from the outside, the chrome piece and keep it from turning. Be careful to avoid locking the vice grips too tightly on the chrome, it will deform. Position an 8 mm (I think) socket and 1/4" drive wrench on the nut from the inside. Holding the chrome and T-fastener with the vice grip from the outside, gently loosen and remove the nut on the T-fastener by loosening the nut with the wrench on the inside. At least 50% of the time, the stud will break. But a successful removal is one which does not deform the chrome. If anyone has a source for replacement T-studs please let me know. Or better yet, send me some.
Sometimes during repairs, the T-fasteners have been replaced with twisted clips. These are not OEM, but are easier to use and remove than the T-studs.
Hope this helps!
Here is a tip added by Dan Diamond of Toronto, Ontario, Canada
I have a 1958 Mercedes-Benz Type 220S Ponton that I have owned since 1972. I find that a stainless steel cap screw of the same dimensions as the T-clip can be used as a substitute. Grind about half of the head off on your standard shop grinder (hold the threaded end with a pliers when you grind).
The resulting ground-down cap screw slides into the back of the trim strip and can be nursed down to line up with the hole in the fender or body. Once mounted, a rubber washer, stainless lock washer and nut gives you a factory-quality installation. (I think the cap screw is M4, and the nuts are 7 mm, but I haven't done this in a while).