My local Lowes used to carry them in section where all the botls and nuts are., they had a selection of studs in 7/16" - 14 along with the correct, flange nuts. I used then to replace all of the rusted hardware on my mac exhaust. pretty sure I used the 2" studs.
I went last week and they where no longer there when I was serching for a set for my other car. Maybe it was just that store though, can;t hurt to check?