Without seeing the part # on the box it's hard to decode....From what I can see of the lamp itself it is a "Guide" unit.

From what I know....the Guide S-18 lamps were mainly used on the car models & the Unity "approved" lamps were offered on the trucks.

However....Both the Guide & Unity lamps are pictured in several different publications as accessories for the trucks.

I don't know enough about the part numbers to tell if a lamp kit offered by GM was actually a Guide or a Unity lamp.

I have installed the Guide S-16 lamps on a few of my trucks, they fit fine & they appear to be a higher quality lamp than the Unity model.

.
Attachments
IMG_8514.JPG (157.43 KB, 111 downloads)
IMG_8515.JPG (256.28 KB, 111 downloads)
IMG_8517.JPG (118.32 KB, 109 downloads)
spotlight2 zzzzzz.jpg (133.51 KB, 107 downloads)