a couple guys on ebay are hawking audax drivers as replacements for the f30/32/50, and they look identical to the originals, but it's not positive whether they the exact same. i'd contact revel directly and ask them.
fwiw, i agree with the f32 recommendation--as a longtime owner i've never heard huge difference between the f30/32 and the much pricier f50--the f50s are slightly bigger and have an extra driver which i assume gives 'em some more midbass oomph, but they don't actually extend any deeper, and the specs are almost identical, so you might as well get the one in prime condition. just make sure you have enough power--they need lots of wattage.
fwiw, i agree with the f32 recommendation--as a longtime owner i've never heard huge difference between the f30/32 and the much pricier f50--the f50s are slightly bigger and have an extra driver which i assume gives 'em some more midbass oomph, but they don't actually extend any deeper, and the specs are almost identical, so you might as well get the one in prime condition. just make sure you have enough power--they need lots of wattage.