OK. I now have a correct wiring diagram for a Pedulla ThunderBass of a particular vintage. It has the Bartolini NTBT-918 preamp with three proprietary Pedulla modules and the "Thunderguts" switch. PM me if you want one. No warranties of any type are offered. Use at your own risk. I wired one today and it functions properly.
Just because one thing sucks doesn't mean something else doesn't.