Welcome to the forum and congrats on the gen one Tacoma.
The dash rattle is more than likely caused by a screw or fastener that’s worked it’s way loose over the last 20 years.
You can try to track it down by going to the general area it’s coming from and seeing if anything is noticeably loose.
Congrats on the new to you Tacoma. Like @Bogunn said you’re going to have to try and track it.
Tracking down rattles can lead to more rattles.
Welcome to the forum.