Or maybe was refretted and the varnish was left off, I have one that looks dark like that for that reason, can't explain the head stock though unless it was painted which I doubt. Looks like non-stock tuners also.
I remember placing an ebay bid on that bass a few years ago. It ended up being a theft recovery, so I'm glad I didn't win that auction.
The bass is a former Rickenbacker employee custom one-off, bill of sale, totally legit, mainly built by Mike himself. It is not in any way production. The neck is essentially a 4002, minus the binding. The body is unbound birdseye maple, like the 4002--but the electronics are totally unique and other than the pickup are mostly non-Rickenbacker. There is a mono and Lo-Z output, if I remember right.
Last I heard, the instrument is back with Mike, so it's a happy ending.
Yes, Mike was a former Rickenbacker employee. The bass was originally thought to be a 4002 prototype, which was just not the case. It's more closely akin to a set neck 4000. Mike probably rescued a flawed 4002 neck from the chipper, then fashioned a nice body for it.
There's a thread I go back and read often. A lot of information given out in the early days there and proving once again, you can never say never when it comes to Rickenbackers.