Are you using OEM lenses, or just some universal cab lights? I had some universal cab lights on my first gen, and promised never to do that again. . they leaked, no matter how good I siliconed them. On my 98. 4, I got some lights from the 2001+ models, and they look SHARP! I would recommend doing that, if you are going to install them. Also, if you didnt know, when you remove the headliner, the holes are already pre-drilled in the lower sheetmetal part of the roof. PM me if you have any questions. I would be glad to help you out!
-Chris-