So, I actually have some nits to pick about this. I've been reading some posts here and other places to that effect, and, inspired by a certain lobster themed Youtuber, I decided to look in to this claim myself, as I believe putting regular guitar pickups in a bass could result in some weirdness like inconsistent string volume stemming from misalignment in the poles and strings.
I bought some magnetic viewing film on Amazon for about $10 and decided to have a look.
First up is the Epiphone:
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To my eyes, these look like rails rather than individual poles.
Now my Gibson NR:
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These look narrower and a little longer than the Epi pickups, but similar.
For reference, here's how my only six-string looks under the film:
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Now I'm not an expert by any means, but I'm starting to question whether Epiphone really just put LP pickups on these birds.
In 2010, Epiphone should have been using the Alnico Classic and Alnico Classic Plus humbuckers in the bridge and neck positions, respectively, on their LP's. These look like this:
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Note the exposed adjustable poles on the front of the covers, and the exposed threaded ends of the poles on the bottom side.
Now let's look at the pickups used on the models of Thunderbird IV that came with the LP size humbuckers:
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Note that the bass pickup lacks the poles protruding through the bottom, as well as four screws to hold the coils to the bottom plate.
I haven't taken the covers off of mine, and I need to take the time to put a meter on each of these pickup to compare them to the 8.1kΩ and 13.3kΩ specs I've seen listed for the Alnico Classic and Classic Plus models, but right now, I suspect there's something special about the bass pickups, although they clearly are wearing the same "BHC" sticker, and I think they share a cover, bottom plate, and ring with their six-string sisters.
What do you folks think?