Last month I made a trivial little cable adapter PCB to use with the Intel SBC 202 double-density M2FM floppy controller in an Intel Series II or III MDS (normally part of an MDS 720 subsystem). The usual SBC 202 cabling has two DC37S connectors on the MDS back panel, one for drives 0 and 1, and the other for drives 2 and 3. (There's a variant that has a ribbon cable to the internal drive as 0, and only one DC37S for drives 2 and 3.)
Photos: https://www.flickr.com/photos/22368471@N04/albums/72157659736489274 Schematic and board layout in Eagle and PDF: http://www.brouhaha.com/~eric/retrocomputing/intel/mds/mds-fd-adapter/ The adapter has no active electronics; it just wires a DC37P to a 50-pin header for a cable to one or two normal 8-inch floppies. I just got around to testing it yesterday, and was pleasantly surprised that my SBC 202 and the adapter worked on the first attempt. The SBC 202 was of unknown provenance so I didn't actually have much expectation of it working. I haven't yet tried more than one drive on it. Intel used radial ready signals from the drives, so the drive(s) have to be configured slightly differently than the factory defaults to be fully compatible with the MDS 720. I have one spare bare adapter PCB which can be made available for $5.95 plus shipping from Colorado if anyone else needs such a thing. I am NOT willing to source the connectors or assemble the boards. You can also order them in increments of three pieces directly from OSH Park: https://oshpark.com/shared_projects/AO0DZTr1 If there's demand for a few units, I can have a small run made in China very inexpensively, probably under $4 each plus shipping from Colorado. Richard Main has made fancier adapter PCBs that also support 34-pin cabling for the use of high-density 5.25 or 3.5 inch disks.