Personally, I would drill into the side of the Strat to install the GK connector using the
supplied plastic plate and keep the original Jack intact. Other than that, I would just
get a piece of scrap mild steel (or ali as Dave suggests) and make my own using a Dremel
or hand files and a drill. Then I would get it chromed or plated to match the original.
But before you start, you need to make sure the socket fits neatly inside the rout
for the jack socket. I've fitted quite a few GK pick-ups over the years, but no one has
ever wanted to fit it in place of the original socket on a Strat, and although I have a GK
equipped bass hanging around at the moment, I don't have a Strat to hand to check for
you.
Andy
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When the going gets weird, the Weird turn Pro.