Agreed, the pickups in mine are really not that great. That's why I bought a pair of the Gretsch Filtertron pickups...they're smaller than the OEM ones, but they should work OK. As far as I can tell, they're rail types so matching pole pieces to strings doesn't matter.
I just have so much going on that I haven't messed with them. I've figured out how I can mount them temporarily in the original pickup surrounds, than I can have new surrounds custom made if they work out OK.
http://cgi.ebay.com/New-Gretsch-BASS-Filtertron-Pickup-CHROME-/290473848762?pt=Guitar_Accessories&hash=item43a1972fba
bought a pair also after seeing your older thread. I have about 5 or 6 univoxs in some sort of restoration - so i will find a home for them. on the weak side if i remember right. 6-7K each.. also six screws on the bottom so maybe guitar pickups???
a few years ago i was able to get some NOS mosrite pups off feebay. Not sure they were NOS as he claimed they were hotter but they were in mosrite covers. one was a HB for the single pup basses. I can't wait to give them a try also.
