Last summer, I looked into replacing the windshield on my 560SL. The part number of the kit is 126-670-01-93. The contents are:
1) Butyl tape, 4200 mm long, ~10 mm dia.
2) Glass bottle with primer, component part A.
3) Glass bottle with primer, component part B.
4) Application sponge for primer
5) Spacing pads for windshield (107 only) 30 mm x 10 mm x 6 mm
6) Spacing pads for side window glass (107 only) 30 mm x 10 mm x 6 mm
7) Spacing pads for rear window glass (107 only) 20 mm x 13 mm x 10 mm
If you've never replaced the windshield or rear window, it's more art than science. There's a copper wire embedded in the butyl tape used to seal the glass. The copper wire needs to be hooked up to a 12V power source in order to "soften" the butyl tape, whether removing or installing.
A good independent glass guy could probably do it in under an hour.
1988 560SL Black/Palomino
1988 300SEL Black Pearl/Burgandy
1984 500SEC Anthracite Grey/Palomino