I finally got my hands on an underpan for my car but it came without screws or anything. does anyone know what size screws i need? I will stop by the hardware store today to get them.

and is it as simple as just holding it up, screwing in the screws and it's done?

 

I believe M6 x 15mm should do it. The bolt head should have a built-in wide washer, like the fender bolts, only smaller. Yes, it just bolts in.

 

awesome!! How many should i get?

 

It's been too long since I've been under her. I'd get 8-10 - should leave a few extra. Buy one to check the size first though (in the parking lot).

 

I think there are twelve bolts altogether.
Three along the back, two (maybe three) on each side and five up front.

 

The question is if there are still places to screw those in to. The clips on the plastic pieces tend to break off and the nuts tend to rust solid. Mine is on with half the bolts and a bit of gorilla tape.