It can be hard to tell about trems. Take this guitar of mine, my first electric that my dad bought me in '69 and I still own, a lovely '67 Made In Sweden Hagstrom Viking I. The trem looks stock for the guitar because it truly is a rarely available, authentic, made-by-Bigsby-for-Hagstrom Hagstrom-labled trem. But it did not come stock on the guitar, I copped the trem NOS and added it to the guitar a couple of decades later.
(Note also the asymmetrical PUP surrounds -- that's because, like an idiot, in college, I routed the top for humbuckers and had to fix later upon returning the original single coils [which are wonderful, BTW, they can hold their own with vintage Gretsch single coils).
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