My dads 04 silvy had crazy bright fogs, but the fog lights on my truck are barely noticeable when you turn them on. So whats the deal? did the 03+ use different bulbs? Or as the relfective housing inside designed better? or a combination of both? Can I use the 03+ bulbs in mine?

On a side note I cant remember what I have to do to get the fogs to come on with my high beams?

 

If I remember correctly the brighter bulbs burn hotter and melt things in the pre '03 fog lights. You will have to find a way to upgrade to the '03+ fog lights to get the better light. Means converting housings and valance if that is even possible.

Try a search on "4 headlight mod" may find the wiring you are looking for. I thought I had it but don't know where I saved it if I ever did.

Attachment 45730

I think this is a pic of the connector but I have no other instructions that I can find and it seems to be for on '04 so I am not sure if yours would be the same.

 

The 99-02 Silverado fog lights take a 880 the 03-05 Silverado take a 9145. you might be able to replace the bottom valance with a 99-06 Tahoe Z71 and thay take the 9145. That might do the trick if you want brighter fogs.

Or you can do HID