Well they are little less than 4 pole guitar minihumbuckers.
I put an Allparts repro EB3 bridge humbucker in a EB0/EB3 conversion, and if I compare it to soundclips of other EB3 pickups (originals) they are not good at all. Very thin. The unfortunate sound of a minihumbucker in EB3's have been discussed before,
but I promise you that Allparts unit is the worst bass pickup ever! But maybe they sound decent in other basses/builds.
As Carlo suggested, I tried to rewind/ beef it up a bit. First With 42AWG (not room for enough wire to do much difference) and 43AWG (more output but not a pleasing sound still) .
Then I tried out winding a single coil SideWinder (like the original mud but smaller) and managed to get a somewhat louder and fuller sound but I still didn't like how it matched the original neck mud.
As I have posted before, I found the best match to be this : a sized down mini sidewinder humbucker with dual mini alnico 5 magnets and 43AWG wire wound up to 27K. This design only came out of desperation, but I find it good sounding, powerful, not harsh but clear and loud. And it matches the output of the neck mud real good. I am currently working on a unit with ceramic magnets, as well as an improvement on the singlecoil mini sidewinder.
Ok, it's become an obsession - but I like the idea of tinkering With this issue.
But I still stress the fact that the sound I like might not be in the ballpark of classic EB3 sound.
Some People rave about the early Gibson mini's, other think they are too thin and just the same as modern mini's.
For reference; I never had personal experience with a real Gibson mini bass humbucker.
EDIT: Oh, I just remembered that I recently did a rewind of the pickups on a Hofner bass (60's vinyl shortscale).
Owner never took it out because of weak output. Did a rewind (I have specs somewhere..) and they really blew me away.
They had four screwpoles and four small bar poles each, seen them on ebay. Pick up one and rewind, that's a good candidate if you are curious! I think they would fit.