The closest "old-style" M122s are the ones with the Model F-style dual-setting feet and a largely metal DIN plug (aka, look exactly like a F122 from the top), but be warned that they, of course, look very close to the slightly later "old-style" M122 that had Model M-style feet that could only be accessed from the bottom but the rest was unchanged (see below for a comparison) and thus important to know how to tell them apart. Most examples of those are very early, being produced largely in only 1986 (although some were made as late as the early '90s despite the third and very different M122 revision already being out). Part numbers 1386887 and 1389152 come to mind. Those would be the easiest to mod for housing a Model F122 assembly.

- IMG_20200526_231155824.jpg (1.01 MiB) Viewed 2632 times
(Ignore the case colour, my example was an oddity with a different case material)