roof rack well nut size

do I have to take it in the *** from the dealer or does anyone know what size to get a Lowe's Home Depot etc???

Ace or True Value probably carry them. They have them up here. If you can't find the right thread (I think they're metric) just get a counter sunk head in stainless steel to match what they do have. I was lucky and had my headliner out, so I used Stainless counter sunks with nuts and used a fender washer on the inside. It's really solid, hehehe. Oh, used some pieces of self-sealing roofing under the rack and between the washer and the roof. Nice and dry now. The hole was half inch I think.