You have been hunting one piece for months. Not a category of piece, the exact one: the right trim, the correct-year manual, the thing that does not exist on any website because it was never important enough for anyone to photograph. And then it is lying on a folding table next to a man who knows precisely what it is worth.
Hundreds of vendors spread across the Fairplex lots with parts, tools, memorabilia, and boxes nobody has sorted since the eighties, plus a full classic car show running alongside. What separates this from a flea market is the crowd. Everybody walking those rows can identify what they are looking at from ten feet away, and half of them will tell you the story behind it whether you asked or not.
Gate 17 on West McKinley Avenue in Pomona, free to get in, and bring cash. Set an alarm that feels unreasonable, because the good stuff is gone before reasonable people arrive.