need 'nut' size

[jjrho]

hi, what is the size of the bolt that would fit in the front license plate bracket holder ? i don 't put plates on my car but i need to use that mount to hold a black anodized aluminum grill at that location.... rather than drilling,etc. , i'm just gonna secure the grill to that.... may even move the outside temp sensor behind the grill..

thanks

j.rho