seller claims 18 volt custom bart preamp from the factory any info would help its MY firstthanx..no matter it is top shelf install

The file for this bass is blank, and nothing was ever recorded for it except a note from Valentino on April 27, 2004 that states:
 
Bartolini electronics
reported installed
 
I'm sorry I couldn't offer anything more helpful at this time, but I can reasonably sure we did not install the electronics here. Maybe a photo of the cavity would help clear up the mystery?