I have a problem with people calling them "MFM drives". The MFM, or any other encoding, is a function of the controller, not the drive. You can use any modulation/encoding that you'd like within the operating parameters of the read/write channels. My 14" SA4008 drive uses MFM encoding, for example. My 700MB 5.25" ESDI drive uses MFM also. Most PC floppy drives use MFM encoding. Neither is apparently what the OP is speaking of.
It's far preferable to identify the drive bt its interface type, as in "ST506 interface" or, better, "ST412 interface". FWIW, I don't believe there was ever a generic name given to the interface; it's always been associated with Al Shugat's Seagate.
It's similar calling the RTC/Configuration RAM device "CMOS". By the time of the 80386, the typical motherboard had lots of CMOS logic ICs.
/rant