Have you posted at LHF? That's where to go for definitive JBL answers. Zilch and a few others hang out here, but all the rest of the guru's are over there.
LHF has a brochure of the MKII with print too small to decipher. Postings infer that the MKII was a version of the original 4344 that was "Japanese designed" or designed for a Japanese audience?, in that, the bass response was not quite JBL west coast. Same drivers as original:scratch2: