Thank you to
@Minnesota Flats for your first-hand accounts of the times. I always love reading honest, personal recollections like this.
I would also say that the '68 Dark Star jam is very very likely to be mislabeled, like so much of this era's live performance recordings floating around the web. That does not sound like Jack to me. It also doesn't sound like
typical/iconic Phil bassing, but it really might be him. '68 would have been early enough that Phil was barely playing bass guitar for 3 years and still coming into his own. It sounds like a pick for sure and not unlike some of the technique and sounds we hear on Anthem of The Sun.
"Go To Her" has long been one of my Airplane favorites and I love both studio versions of it (there was one recorded during the Takes Off sessions and one during the Surrealistic Pillow sessions). Somehow neither was chosen to be on either album, when I would argue that it would have been the best song on either release. Regardless, both are great examples of the Jack's modified jazz bass.
Regarding the output jack on the jazz bass, I've never seen a photo where two cables were visible and I believe the odd positioning of the output jack was just a creative decision on Jack's bass when it was rewired to accommodate the extra pickup. My best guess is that a hole was drilled in the plate
for the single/mono output jack in the unused area between what would have originally been the concentric vol/tone stacks for each of the original pickups, the controls were scootched back and the single/mono output jack was inserted in the hole closest to the strings. It looks like the original output jack hole was used for the added P pickup's volume (if not a 3rd vol/tone stack). Hard to say though, as I've never seen a particularly clear, close shot of that bass. Again though, I've never seen two cables coming from that bass, so I don't think there was an extra output jack added.
One of my favorite recordings of that bass was the Takes Off tune "Let Me In", which I doctored up a bit to isolate as well as possible, Jack's bass, Skip's drums, and Paul's vocals, from the rest of the mix. Again, one must take into account Jack's unique technique and the (most likely) Fender Showman amps, but the tone is killer here too: