1984 Trek would tell me pre indexed which means you can use standard cable housing. Ferrules are dependent on the frame. You may need a reduced ferrule for the frame/housing contact but aren't necessary on the derailleur contact. (ferrules look nice and clean but you can just cut housing and grind/file the end square) Be sure to properly collapse the housing when you install them. Install everything tight and squeeze levers and pull shifters without actually shifting the gear. You should have a noticeable slack in the cable. Then loosen the locknuts and take up the slack. If you have indexed shifting, you will need a indexing cable housing and not standard brake housing. Indexed cable housing was made with wires running the length of the housing(verses coils) and prevented cable collapse, thus slop in your shift. These do need ferrules and many times are pre made to size with sealed ferrules. They also improve friction shifting. Making things crisper.