ID question

[Devere]

I have a P-Bass that I think is a 1974 as too ser#. It is natural finish with rosewood fingerboard. What I don't know the story on is that is has a metal pickguard in black and also a special tone control with small toggle switch. The switch changes the tone slighty.
Can anyone help me with this identity?

 

[msb]

Neither the metal pickguard nor the toggle switch would be original for a 74 . Someone has tampered with it .

 

[bolophonic]

If it has a series/parallel switch on a Precision, then I doubt the pickups are original. Some photos would help.