(copy and paste from my reply to your post in the other place : )
Not an '87... 90s+ as far as the bike goes. In the 80s Prologues were the funny bikes only (Circuit and Peloton were the top of the line Non-Paramount bikes). The 6400 group might be a later addition to this bike (it run from 88-90)... Does it have an Aluminum frame? Look at the frame sticker
Or... are you talking about a Prelude instead of a Prologue? (and Preludes did not come with anything like 6400).
Oh... and pictures will help