Hello Keith,
I use the GM vintage Heil mic on my TR-6 and have had very good audio reports... If you buy one I'd make sure you order the vintage Heil cable to go from the mic to the T4XC.. I have a C line also, and have yet to used the GM vintage heil on it but would say it would work as well as on my TR-6
Good luck,
John KG9JA
