From looking at the pictures I would say: Schaller M4 Sealed Bass Key Enclosed, Bass Side, Chrome, 12:1  
Retail Price: $32.00  
Found it on: allparts.com  
 
It's the tuning key on my 83 and 87 Spoiler
Good luck with your new Bass!

Congrats Claudio!!

Thanks Guys!!
I cant wait to get it here...
I'm hoping that everything will be ok with this oldtimer...Pictures are just that...
The seller told me that he remove the thing that is in place of the E tuner and looks like no modifications was made to adapt the thing to the bass. I will call Val, to check with him how busy they are to make some adjustments and tune ups. I'll keep you posted...