SME 309, V and IV cannot be mounted on old sprung Thorens, or even LP12. The arm is too heavy for the designed load of the tables. Stick to light arms like the current SME M series or the older 3009 series.
Thorens TD 166 MkII with SME tone arm
I'm planning on upgrading my TD 166 Mk II with an SME 309, IV or V tone arm. Has any one done this? any advise? I haven't bought the tone arm yet.