Yes it has an 8 digits serial# and the black colour is absolutely factory, not a repaint over a cherry SG. Definitely no black binding, the ebony fretboard is exactly the same as the one on my 1974, the only difference being the '76 having slightly wider and flatter jumbo frets than the '74. As you say it possibly was a custom order but I can't say more as I'm not the first owner, not even the second one, as I bought it second hand in a guitar shop in the UK. And yes it's a cool guitar, it plays like a dream and weighs a nice 7 Lb 5 Oz. My '74 is 10 Oz heavier... but it has a Bigsby... and sounds even better.