I wonder if they have archived records of their appliances. There is no product history section on the website. It may be worth your while to contact them and inquire.
Familiarizing yourself with the various logos MW has had will give you an idea of the age of its cleaners, so I will post what I have found online. Depending on how involved you want your MW collection to be you could also seek to purchase MW catalogs on ebay or elsewhere. Just some thoughts.
An overview of Montgomery Ward from its homepage:
For more than 140 years, "Montgomery Ward" has been a well-known and trusted catalog brand. In 1872, Aaron Montgomery Ward established the first mail-order business with an innovative single-sheet catalog offering 163 items. Montgomery Ward's superior service and impressive assortment of goods led to rapid growth, and by 1904 the original Montgomery Ward company was mailing catalogs to three million customers.
In 2008 the "Montgomery Ward" brand was acquired by a subsidiary of The Swiss Colony, Inc. (now known as Colony Brands, Inc.), a family-owned direct-mail business that strives to continue the heritage, traditions and values of the brand that were inspired by the founder, Aaron Montgomery Ward. Today, Montgomery Ward offers one-stop shopping for quality items at affordable prices—and quick, convenient delivery.
1960s logo (marked as 1872-1968, but that doesn't seem correct):
