I just bought a box of these as replacements on my Summit 450 and I don't like the fit. It's sloppy, not precise like the original. You can see the difference in these photos.Those studs are part of the end cap. The nuts are self cutting nuts. The nuts you want a 7/16" head x 1/4" shank.
https://www.amazon.com/exec/obidos/ASIN/B0041C6LYW/tvwb-20