Based on popular demand, we've developed a re-issue of the Tobias Growler preamp harness. You can find the diagram for it here:

We've built a few extras that can be purchased directly from Bartolini in our Web Store:

Since you have found your way to this page, you can get a discount on a Growler Re-Issue Preamp Harness by entering the code Growler20 at checkout. This offer will only work while we have stock. We only have a few, and it is unlikely we will make them again for a several years. They are a huge amount of work!

Attached is also a very old Tobias Growler wiring diagram for your enjoyment.