Thanks, Fred! That makes sense to me - I reviewed the restoration photos I took of the washer and its components and noticed a date of 65-11 on the water valve so it's got to be a late '65 or early '66 model.
I do indeed have some of those promotional postcards - you sent me home with quite a few promotional items when I picked up the Tappan microwave, thank you!! I still think the woman in the photo is an early prototype of the Karen Walker character from Will & Grace... LOL