The '88-92 "aluminum" slave uses the "black" coupler and the line used on all Ranger/Bronco2/Explorers up to the end of 1992.
in 1993 Ford switched to a glass reinforced plastic slave cylinder that
I believe is better than the earlier ones, but this requires a different
clutch line, one that uses a "gold" colored connector (they aren't compatible)
The later gold colored quick connectors are slightly larger than the older black ones. I read a post a while back on TRS where someone in this situation simply filed down the end of the gold quick disconnect to make it fit. I'm not recommending this method,but there it is for your consideration.