any hole they can squeeze there little bodies into. i thought i had it all figured out. i loaded up the truck with moth balls. the only thing they kept out was me. so i blocked all the hole i could on the 6100 including the lever holes with chicken wire. that will fix them as i chuckled after getting my breath back from the mothballs. one day i went out to run the truck and iee all this mouse crap on the floor and said WTF. i lifted up the seat and there was a nest the size of a bowling ball from all the soft fuffy stuff from my new seat cover job. so i went to start the truck and saw a flash at my foot on the starter button. he was hiding under the mat and exited stage left out and under the seal for the steering column. i took some flashing and riveted the hole closed as tight as i could and now i can say that trucks cab is mouse proof at this time.