Though it's a joy to return to the University of California libraries, one effect of the recent past has been to send me to digital primary sources, most recently Modena B with its large corpus of Burgundian office music. Besides Dufay's hymn cycle, it contains a group of Magnificat antiphons (already edited in the new Opera Omnia). Although Dufay wrote no Magnificat in mode ii, well represented among the antiphons, there are two such works by Dunstable & Binchois.
What makes me curious is that modes 4 & 7 are missing. It seems to me that I've come across later collections with 6 Magnificats (or even fewer) that include rubrics for making substitutions, though the particulars escape me. Can anyone here jog my memory?