Below photo from Hap Alzina catalogue showing exploded view of the type 16 and type 366. Regret does don show which fitted which bike.
The 16 is a bit more substantial than the 366.
From 1969 Clarks cable catalogue and Amal papers;
366 takes a throttle cable with a 3/16 inch barrel nipple and a 1/4 inch (smallest diameter where it fits into the assembly) throttle cable stop ferrule. 90 degrees of movement gives 1 inch of cable movement.
16 takes a throttle cable with a 7/32 drum nipple and a larger 3/8 inch (smallest diameter where it fits into the assembly) throttle cable stop ferrule. 90 degrees of movement gives 13/16 inch of cable movement.
