Yes it’s an output jack, Superficial, bigger than any other I’ve seen.
I bought a 2012 Squier classic Vibe neck from France Guitar when they had exactly the one I wanted. They have a good range of Fender necks at sensible prices.
My son has a Warmoth neck and I’ve got two. Junior has a vintage style Tele neck with gloss nitro, stainless frets and a 10″ radius, it’s a delight. I’ve got two modern style with double expanding truss rods, 10″-12″ radius, dunlop frets and matt nitro. One is a Strat with a modern C which is just like a Squier classic vibe. The other is sort of flat C Tele.
My two required a few hours work. Fenders have very rounded fret ends, sometimes too rounded and it’s easy to lose the string over the edge when doing vibrato (my vibrato is clumsy). Warmoth leave the frets with angular ends unless you pay them to do otherwise – you will probably want to spend some time with a polishing mop in the drill bit to smooth them even if you don’t fully round them (buy a fret board protector before you do so). You also have to clean the nitro off the frets youself and spend a few minutes with car polish on the back of the neck to make it really smooth. I lowered the nut slots on mine, junior left his standard. Fender drown their maple necks in thick varnish which mean that even their medium jumbo frets feel a bit low. Warmoth don’t so the frets feel full size.