Do you mean this drive? To me it looks like just a different mechanic form factor. Isn't this a drive from one of those desk model PDP8 machines? It seems to be optimised to be used for a fanless construction. Normally there are fans on the mack of these drives. But I'm just guessing here. But I'm sure it will be compatible with a normal RX01 drive.
I don't see the pic on ebay any more but that is what I was referring to. It seems to have a place to mount rails on the side. Will it work in a normal DEC rack? Will I need to add fans?