I don't think the 600 neck will fit on a JTV as I have a Warmoth Strat neck and it won't fit on my 300 Variax. Not even close. But as stated regular Strat necks do fit on the JTV's. Warmoth can set you up with a Strat neck for under $200. Be advised it will most likely need a fret leveling and crowning which will cost around $200 on top of the neck costs. Of course this would void your warranty if L6 was to know about it. If something did go wrong with the guitar putting the original neck back before sending it in would negate this issue if you kept your mouth shut about it. Obviously.

Same tuners. Peg holes on the new neck were slightly larger, but once tightened down, no excessive play. Feels fantastic.

Anyone else tried this yet. You will have to trust me that this works. Despite what a few may think to the contrary, this Japanese made neck from my trusty old unused Variax 700 is much better than the original Tyler designed neck and feels very familiar in my hands with hundreds of hours of playing and gigging with it. It is still in perfect condition apart from a little fret wear but the action is great and intoned perfect. You may notice that these are not the original tuners but they do allow dive bombing and still she stays in tune.

No problems fitting, just the extra hole needed pre drilling with a 3 mm bit. Both E strings are pretty close to the edge but thus far with some pretty heavy testing have stayed put. I think in all probability this neck will stay on this JTV.

Just thought I'd let you know.

Thanks for the compliment.  I bought some water glide paper.  You then can design to your liking and print iit out on your computer.  It then takes a few coats of acrylic spray. You have to wait over night for each coat to dry.  Especially the final coat.  I put three coats on. It was also helpful that I had a template of the headstock.  I just printed a couple copies in Draft mode on regular paper to make sure everything lined up right before I printed the final