I'm posting this in case it helps anyone else. I put in a NOS 1989 T-Bird headlight adjustment screw today. It's doable, but I found that for 1989 Ford switched to a metric thread from a SAE one. Luckily I had a tap set, and I used a 6mm x 1.0 tap. It went in easily as soon as I did that. I also had to unscrew the plastic spacer that came with it, but that was trivial. Anyhow, just a little piece of information that might help someone.