This is another Ray Shulman (Gentle Giant) mystery. Some of the tracks on their 1977 album "Missing Piece" sound different than his usual P-Bass and here's one sample soloed:
Doesn't sound like a Jazz Bass either. Could it be a G-3? There's something there that tells me it's a 3 PU bass.
EDIT:
The Ripper bass with both pickups on in parallel sound a bit like it too.
http://www.flyguitars.com/gibson/bass/1978gibsonRipper.phpBTW, the first sample has clearly pickup's out of phase and the last one in phase, not vice versa as it reads there.