I have the factory cab lights on my 92. (5 lights).
Going from either side to the center of the cab.
-first light is 5 inches from the side gutter to the center of the light
-second light is 17. 25 inches from the center of the first light to the center of the second light
-third light is in the center
If you want I can e-mail you a picture. Just send me a pm.
I hope this helps.
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Al