In 1984 the thread changed in most Camaro Firebird TA's with DRUM rear brakes to a metric thread.. not all but most.

This is for the 1982 & 83 .. and any 84's that may have had a AF thread.. or for that matter a diff change too on some cars..

THIS IS FOR mainly 82 & 83's with AF threads... two brake lines. pre bent ready to install.