I just bought this one - a Japanese market only (from Japan) 3-pu bass from (year?) that originated in the '90s - made by ESP - the Bass IV (riffing visually and in that tricky numerical turnaround... the early '60s Fender VI)
View attachment 4574376
'64 Fender VI - the oddball guitar/bass that a few players made good use of, including Jack Bruce before settling in on his Gibson EB.
View attachment 4574377
Painted by the Fool - currently in the Museum of Modern Art. Looks like a bit of modification w/the bridge pu.
View attachment 4574391
That Bass IV looks great! Is it a short scale?
Roy Babbington (Nucleus, Michael Gibbs, Soft Machine) used the Bass VI to a good effect. In fact I don't know if he used a 4-string bass at all in the seventies when he played the electric.
Sveinung "Thunder Thumbs" Hovensjø is a long time VI player. I love his playing on Terje Rypdal's albums.

I don't get some people.