The Economat was made up through '57, the WGH. G for '57 and H for the higher end Economat.
Not sure if this was a contractual thing with the sale of Bendix to Philco from Avco or not, but it doesn't make a lot of sense to have not only two versions of front load washing (Gyromatic & Duomatic), along with the Economat AND Power Surge top loaders available in '56 and '57, AND Philco having their own top load washer available in '57, based on the Dexter-Beam hybrid.
Ben