From the Lone Sentry site, a photo of the evolution of the MG34. The MG34T is second from left. I confess to not having read of the MG34S anywhere else, so I don't know what it is, or how it was used. IIRC, the MG34/41 was an intermediate step between before reaching the MG42, and saw action in North Africa? Not sure...

MG34 progression to MG42.

The german Gewehr G41, the upper rifle is the Mauser version, the lower on the photo the improved Walther version.