@sudsmaster
Later though research found out the Sunbeam shown in snaps one posted above (sold on fleaPay) was one of the last "MM" (IIRC) models Sunbeam sold of the Mixmasters, commonly and often referred to by collectors as "PlasticMasters"
Though still incorporating the bowl hugging beater design in many models, these last of the series were mainly all plastic or metal upper housing with plastic underneath for mixer, all plastic base. Some models did not have the bowl shifter lever either. Port for attachments was removed and the area became the spot for beater ejector button.
Sunbeam featured an "American Classic" series of mixers all these lines that came out in the 1980's or 1970's (cannot remember). This entire style is referred to as the "Brady Bunch" since Alice had such a Sunbeam in the kitchen. Would love to say "Mrs. Brady's kitchen" but don't think she spent much time cooking....
All and all plastic aside these later mixers aren't all that bad according to some. Certianly are better than the China built stuff that came later (Sunbeam switched production from the USA to Mexico, then later to China). Underneath the housing these mixers are pretty much the same as the "V" and Mixmaster series that preceeded them, and IIRC the 12 series as well. What is different in some respects (again this is from reading comments, cannot be sure) is that certain tweaks were made to give these units more power for the watts. Oh another good thing is that the plastic housed units are lighter. This makes them easier to use when detached from the base as portables.
Sunbeam is one company that has been raped and pillaged by corporate raiders for the past 40 years or so. This accounts for the often cheapening of the brand and attempts to simply trade on the fame rather than produce a quality product.
Sunbeam in it's early years never pulled a "Dormeyer" that is having several flavors of mixer on the shelf at the same time. But later as the company changed hands like a cheap tart at a prison rodeo that changed.
In general methinks other stand mixer makers suffered from Sunbeam being the "Bendix" of mixers. That is having patented the bowl hugging beater system others had to find other ways. Hobart went one way when introducing the Kitchenaid mixers to housewives, HB, Dormeyer, and the rest did so as well.
Really is some what of a shame Sunbeam didn't decide to keep the "Power Master" series. Bet if they had worked out the bugs those units would have been the rival to KA mixers as intended.