I don't have specific experience with an 87 260E but I 'd lay bets there are three (two at least) metal tabs extending down from the bottom of the upper seat, secured to the body with screws; (take the seat bottom out first) then unscrew them and then push the seat back up (vertically) and you should be able to remove the entire seat back. The re-installation should be obvious.

Hope this helps.

__________________
Simon Shearer

1986 420SEL

2000 Porsche 911 Millenium Edition Carrera 4
2010 Lexus RX 350
2002 Kia Rio
2002 Hyundai Accent