Alternator valve cover interference.
Al 95 Z28, it's alive! GM AC compressor seals work on the steam pipe! The trick is waterproof valve grease to keep the banjo bolt from tearing up the rubber.
Hope that helps.
EDIT: Noticed you said just BEFORE the fan, that would make it 4" 3/8ths long. Through the center It's about 5" 1/8ths, no fan.


