Re: Gibson Explorer pickup spacing
The short and snarky answer is that it doesn't matter. Don't even bother worrying about it.
To elaborate, pole spacing is pretty much irrelevant in the sonic sense. It's an OCD visual thing for some people; that's it. And it does matter if you are talking about ordering covers that fit a particular screw bobbin, of course. But as far as sound? The extremely minor difference in spacing between regular spaced and trem spaced falls well within the normal "slop zone" for pickup poles, such that the slight alignment differences make no sonic difference at all. Any tonal changes (if any) would theoretically result from the slightly different coil dimensions, not from how well the screws align with the strings.
Most Gibson humbuckers throughout history -- including today -- have had the narrow spacing. But Gibson "T" pickups do have the 52.4mm spacing (pretty much a Trembucker). So to answer your question directly, if your guitar came with the 496R/500T pickups, your neck pickup will be 49.2mm, and the bridge pickup will be 52.4mm. However, you don't need a Trembucker for the bridge position. And not only do you not need one, but there is also zero advantage to getting one, short of looks. I'd say to get one if you want...but don't go out of your way to hunt one down, and certainly don't bother to special order one.
