Maytag (now owned by Whirlpool) has a number of designs that you might
call stackable. A laundry system has a top load washer on the bottom,
dryer on top, and the it can't be "unstacked." The Neptune Superstack
is a front load washer on bottom, dryer on top, and while they may come
into your house unstacked, they can't be operated unstacked. Finally,
some Maytag front load washers can have a dryer put on top, but they
can be operated side by side as well.
So, which do you have?