I found a little treasure trove of info .. I'm happier now.
Models of the 4865 for the AT have just a DB37 connector. They are
supposed to get power and signal from an additional card that goes into
the machine, as an AT normally doesn't have an external floppy port.
Models of the 4865 for the PC and XT have the pigtail power connector.
There is a Y cable to split power from inside the machine to the drive,
and a bracket that accommodates the new power plug that is needed by the
pigtail connector.
I traced the voltages out already, but getting confirmation was nice.
If anybody ever has a desire to connect a 4865 to something, let me know.
Mike