G Distributor question

["Richard Osborne" <richard@xxxx>]

Good Evening,

I just put a new vacuum advance on the distributor in my G and noticed
that the return spring for the advance is missing. 

I am wondering if these springs are interchangeable with later model
springs? I don't have the G spring to compare to another. If it is not
interchangeable, what is a good source for these and are there diferent
tensions available to control the rate of advance?

Thanks,

Richard Osborne