As I was getting into my car today, I heard a thump, looked on the floor and there was the part pictured below, I figure it's important and as soon as I find where it's missing from I will put it back if anyone knows where it belongs. Just kidding but there's a lesson here to check and recheck as many parts as possible every so often, I don't know how long the nut and washer has been missing but I will replace the missing nut and washer with the locking types.