GP403 just put dimable LED's in his cluster but I think if you go to the next page he says he took them out. I'm pretty sure somewhere in there within a few pages of this link he gives the source where he got the LED'S.
https://www.gbodyforum.com/threads/project-blue-book-87-cutlass.57731/page-6
https://www.gbodyforum.com/threads/project-blue-book-87-cutlass.57731/page-6