I was under the impression these were RK03s. Now I
understand they are indeed RK01s.
--
DEC never sold Pertec drives, though lots of third parties did.
They most often showed up as Plesey add-ons.
What you probably have is some variant of the D4000. They came
as fixed/removable, just removable, 2315 front-load or 5440
top-load packs. The 2315 flavor was compatible to RK05's, 5440's
were 5mb.
Just checked, I have the D4000 service manual scanned, but it isn't
up on bitsavers. I'll see about getting that done.