Big Tex,
If you do an Google search and input "Guaifenesin USP 99.9%" you will find an company that are suppliers of pure Guaifenesin USP 99.9%. It is quite forgiving when it comes to salyicates - which I never really had to watch because of this guaifenesin. I found that only an few blocked the guaifenesin and then not for long.
Good luck in your search.
Chy