Cabinet width.
The DD's are either 24" or 27"
belt drive is 29"
The Whirlpool made, standard or super capacity, <span style="text-decoration: underline;">filter on top</span> dryers are always 29"
wide. Originally a perfect match with the belt drive washer.
Visually, unless a picture has been modified, it's easy to see the difference when comparing side by side.
Of course if one has a look inside the washer, or can see the back then it's even simpler.
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This laundry pair is going on 40 years old and ....it's still going.
IMO- still looks almost new.
I remember buying a 1991 pair like this, in almond, as a gift for my mother.