Interesting B tension screw.
I think a 12T on a 6spd FW might be hard to find.
The shifter will only index 6 speeds, but will handle 7 or even 8 in frictions.
I believe these shifters were subject to the 'teeth' breaking off the index pod or whatever shipmano called it, it is in the upper right in the pic
In this pic the 'teeth' are broken off
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk