I'm getting the upholstery on my LSV locker tops and engine cover replaced by a neighbor. I took some of the upholstery off of one of the lockers. I had a problem removing some of the screws that hold the strut support bracket to the aluminum board. The threaded tube thing that the screws anchor into had rusted a bit. I need to replace the threaded tube thing, but I don't know what it is called. From the side, it is T shaped. From the top it is circular with a hole in the middle. Also, it has 3 teeth on the edges of the circle that sink down into the aluminum board when it is tightened. Can someone tell me what to look for?

Thanks