If the windscreen from the 1988 has come from a Tricolore then it might not fit(?). As far as I know all 851/888 models (Apart from the Tricolore) have 2 types of top fairing/windscreen. Ducati did not have an exact date in 1992 when they changed over from old to new............so the only way is to look at the part number on the inside of the top fairing. I attach the photos of the 2 part numbers I know. If you want a new original windscreen for fit your bike I can definately sell you a new one if you confirm your top fairing part number.
See this link :
