Thank you for your assistance. Well being there was so much dirt inside the recessed torx that I could not even tell there was torx T15 recessed for a torx driver to fit inside the head (it is a combo for both a driver and socket), as before I could only see the outside splines being a torx socket would fit.
I still will need the socket size as when I placed a T15 torx driver into the head--it shattered the cheap metal torx head [not the torx driver--but the head itself literally fell apart (not stripped) when I twisted the torx handle] as the head crumbled into pieces.
The heads fell apart on both hedlight set ups. Really?
GM used to make durable parts, so this is really chapping my hide...
So I need the correct torx socket
size which I asked for to begin with and get lucky that the torx head will hold up or otherwise I have to buy a whole new headlamps assemblies for both sides which is riduculous having to do so for a 15 YO truck because of inferior metal was used for the torx heads.