Rodime 552 drive interface?

All, a friend of mine had a question this group is probably best to answer: ------------- I am trying to determine the type of interface on an old Rodime 552 drive. It has 26 pins. SCSI has 50. IDE has 40. The old MFM used two cables, not one so I don't think it's MFM. I did find a listing for it at one of the surplus places in a table which lists interfaces, but all it said was "26 pin". I'm trying to figure out if the thing is actually one of the more common interfaces with a funny connector--perhaps all the GND pins have been combined into one reducing the pin count. This model of drive is found in the old Apple Hard Disk 20, which was the ancient floppy drive interface external hard drive used on Mac 128Ks and 512Ks before the Plus with SCSI came out. ---------------- any help for him? Thanks in advance, - Mark