Not sure, but if referring to one-piece crankarms, three different arms at least? "Flying Merkel"
one piece crank arms seem advertised with only one style ring, a 4-hole kidney bean but thoughts are there were other ring designs made for this over-sized crank that came on Merkel machines. Not sure, but some suspect the simple 5-arm ring and/or other designs that had the 2" drive pin offset were on Merkels. Do not know if these "Merkel" cranks were used on other Miami models. They certainly only fit chainrings with a 1" (51mm) chainring hole opening and large, 10mm drive pin hole opening. Another one-piece crank Miami made was for a Sweetheart as AS mentions above. This sweetheart ring also has the large, 1" crank arm opening but short, 1-5/16 inch(11/32) (34mm) hole spacing.
Then there is the ring and crank below, supposedly Miami. It has a 15/16 arm opening, smaller 8mm drive pin hole and the odd 1-5/16" spacing similar to the Sweetheart below it.
And a potential Merkel ring below with 2" pin spacing.
All three together requiring different one-piece cranks.
happy to have an appropriate chainring for my project but this spacing for the engagement pin is a new one on me. none of my cranks fit! so... while I search for the correct cranks (hint, hint) I'm wondering if the spacing of this chainring indicates a certain time in the evolution of Miami...
thecabe.com
Left out for the real enthusiasts were the Center Drive setups that did run a single special crank arm. Only those lucky enough
@New Mexico Brant to handle them can talk specifics about that arm. So 4 total single arm cranks? Not sure about the early teens & back d&j arms or crankset specifics as they don't show often.