Here are the details on the 4003SB.
1) Very bulbous shaped head, not wings.
2) Only came in MG
3) Truss rod adjustment@ bottom of neck, not under TRC.
4) Very thick body and neck, a little heavier than a 4001 or 4003
5) Non vintage knobs (silver tops)
6) It IS a neck through, NOT a set neck.
7) NO horseshoe, it is a stock hi-gain from that era.

IT is a stereo model, not mono, like the V63.
9) Also notice that the toaster is in the 1" position, not closer like the authentic pre 75 models. It was not designed with any real thoughtful or authentic engineering.
I have made a few mods to make it move authentic like a V63 larger treble pickup surround, vintage all black knobs, had both jack wired in mono.
And it does sound awesome.
Rick bass fanatic. I own and play several professionally. I have a passion for the S models.