the JCW part/item number is: 184852with description: "steel core window channel"
price for a 6 ft stick is $28.99
its basically a "U" shaped channel with round beaded edges at the open side, black fuzzy/felt on three sides in the channel, with a black rubberized outer finish; best of all, its flexible and can be shaped into the gentle curve of the top of some car windows, like on the 57, so that it matches the curve of the top of the glass as it meets the upper travel/channel in the window opening. I attached mine to the window trim piece first using some adhesive, then when dry, installed the trim piece back on the car...
now, if I can get the rest of the weatherstripping done this easy, it will be almost like taking candy from a baby!
good luck if you try it.
Mark