Part Number for the over the cab light bulb

[jsbihn]

Hey all,
Well I go down to the local parts chain and ask the kid behind the counter what kind of light my over the cab OEM ambers take.
You know the stock OEM marker light over the cab of the rig and also in the back that are required by the DOT.

Anyways, Skippy tells me that these OEM ambers are aftermarket. I explain they arent and again he cant find them, same with two other parts stores....

So now I am wondering if you guys happen to know the PN for the light that comes stock over the cab.
(the bulb not the fixture)

Thanks