I just had a number of interior doors replaced in an old house that I am
having renovated. The door replacements were done to make all of the
interior doors in the house match instead of having mismatched door styles
throughout the house. The original doors were 77" to 78" high. I had the
doors replaced with inexpensive hollow core Masonite veneer 6-panel door
slabs.

The replacement door slabs were 80 inches high, so they had to be cut. But
the cuts meant that either the top or bottom ended up as just an open hollow
space between the front and back veneers. Somehow that doesn't seem right
to me. What do contractors normally do in this situation? Do they really
just leave the top or bottom open like that? Do they try to fill in the
space with a replacement filler piece?

When I search in stores and on the Internet, I can't seem to find interior
door slabs that come in any size less than 80' high. Am I missing
something? Don't manufacturers sell hollow core doors that are 78" high so
that when they are cut a little shorter there is still a solid end piece at
the top and bottom?

Is my only other option to use solid core replacement interior doors? And,
if so, do they sell solid core interior replacement doors that are 78 inches
high?