does anyone know what size the bolts are for the factory skid plate on a 99 that bolt into the framerail?

 

I'm not sure, though you could always go to your local ace hrdware and grab a couple that look about right (I'd start with 3/8), then ask them if you can try a few on your jeep parked outside (they have always let me do this) then figure the correct size and thread pitch you need. Then you can get a couple lengths, around 2" or less should be about right. Just return the ones you don't need. Or save them for some other project, you never know. Besides they are only .50 each or so...