I've always wondered about the origins of the Vista Mixmaster myself... Funnily enough, the model number is V-14, so I guess Sunbeam was superstitious... No model 13 Mixmaster! LOL
I don't know exactly when, but the TOL Wards Signature stand mixers were rebadged Sunbeam Vistas at one point.
I can't help but wonder if the Vista was the 'in-between' design that didn't quite make it when they were transitioning from the bullet-shaped Model 12s to the MM style Mixmaster. Mix-Finder dial of the Vista mixers is very close to the ones in the MM series (and if anyone ever sees just a dial, please let me know...I need a couple... LOL)
One thing I do know for sure - the early Vista Mixmasters weren't seen in my neck of the woods. They did seem to re-appear in the mid-70s and seemed to be an exclusive with K-Mart here in Canada. Those models didn't look anything like the original V14 series, though.