Anyone know what I need to get the plug out of the pass side head so I can install a fan temp switch in my 85 LG4? It's a bit cramped there. Looking at it with a mirror, it appears to be a square drive but a 3/8 won't fit it?

I've got all the pieces/parts to convert to electric fan but I need to get this plug out so I can install the switch.

Thanks for any help.

If it's square it's either 3/8" or 1/2".