Chandra Bajpai:
The black faceplates were OEM drive face plates. The original version of the D had custom white ribbed faceplate for the drives (miniscribe were the first) but they didn't last very long as we used many different drives: seagate, miniscribe, microscience were a few and it wasn't cost effective to get custom face plates made for each drive and some drives (e.g. microscience) it would be difficult to mount a custom face plate. Frankly, it looked ugly but customers were breaking down the doors to buy the Model D anyways. btw: the last model D looks like it has a microscience drive.

...That white faceplate is a microscience faceplate and not a Leading Edge face plate. The difference is that the "ridges" about the keyboard controller extended across the drive face plate (ribbed) to match the ribs around the power & reset switch. Like I said it must be very rare since it was the first run of Leading Edge Ds.