DURBSMAX

Hello All, First post, but I have a specific question about 1AAuto mirrors. I just bought a set for my truck but one of the mounting studs was broke off upon arrival. I know the optional 4th stud is threaded but are the other three as well? It would be nice to just back the broken one out and replace it alone if possible. I know PGAMBOA knows his stuff so I thought I'd ask here. Thanks! Update: After some trickery with some vice grips I did find that all the studs are threaded in the 1AAuto mirrors.