By the 1987 model year Shimano had completed its move to SIS. Indexing was available from the top-of-the-range groupsets down to the work-a-day L Series Light Action sets. Only the basic Z series and the evergreen New 600 EX 6207 derailleurs were friction.
Most importantly, the 1987 model year marked the move of the mountain bike components over to SIS. Remember this was a time when mountain bike sales were roaring ahead, while road bike sales quietly slumped into oblivion. Shimano had tested SIS on road components partly because they were a small commercial risk, now it was ready to go mainstream.
Note, also, that the catalogue claims to describe ‘the complete line’, but makes no mention of three speed hubs, nasty steel Tourney derailleurs or ‘inexpensive’ 5 speed freewheels. Like Leon Trotsky in the famous photo of Lenin’s speech in Sverdlov Square, they have been air-brushed from history.