Help! speedo cable

[elcam33]

i have a 1969 vette with 350 4 spd does anyone know what the diafram that the speedo cable goes into in the right side fender does

 

[Vettehead Mikey]

Not sure what you're asking about. Got a pic?

 

[kbunting]

i have a 1969 vette with 350 4 spd does anyone know what the diafram that the speedo cable goes into in the right side fender does

Do you have cruise control on this vehicle
It might be for that, if your car has it.