The K-mount Takumars were also available in a 135mm focal length. Nothing to write home about, unlike the old Taks from the M42 years. The SMC Pentax lenses (original K mount lenses) were mostly based on the M42 mount Takumars. I'm not sure if the original SMC Pentax 50/1.4 had thorium in it, like the Super-Tak and SMC Tak versions that preceeded it, though.

-J