I noticed in a window reflection that a brake light was out, what a pain to change! but easily done in 5mins.

i also noticed the top of the tail lights is actually just a blank plate! i was thinking of drilling a hole and adding another brake light.

then today i see a white mk2 with the tops of the tail lights lit on!!! is this a mod? or did lexus after 1999 actually use the space on top?

if so anyone know the part number for the harness?

Yes after 2001 there was a small facelift of the GS, the rear light clusters were changed to a more modern look.

These can be swapped with the older ones and yes you do have to do a small mod to the loom.

If you do a search you will find that a few members on here have done this and there are a few how to threads knocking around

HTH
Paul