Hipshot BT1 D tuner. Was fitted to my Maruszczyk Jake, but that's being moved on. You know the deal with these, IMO, an essential bit of kit for a 4 string. £50 posted to your doorstep.
Quality bass. I had a GWB35 and that was pretty damned good, so I always fancied a 'full fat' one, but other basses came calling (as they do). A photo of the buckle rash would be welcome, as you have piqued my interest.
The sound from that seems to sit perfectly so I'm guessing the new one will do the same (plus you have the vintage switch option too). If your singer doesn't like that one, tw@t him on the head with it.