Prior posts have been really helpful, but I have a dilema. I cannot seem to identify the GLR or rather which one of possibly two, side by side is it, or both. Please help.

2001 for F-350 super duty 7.3l. Have a photo but do not understand how to attach it here

There are two glow plug relays, which are attached to an aluminum ventilated housing. They are part of the glow plug controller. Sounds like you located it.