I have a 48 inch width between two walls with a current 48" vanity.
The vanity fits very snug.

On top, there is a cultured marble top, but it appears to only be about
48 inches to fit between the walls.

Any new vanity tops i see only come in 49 inch versions (to allow a
little overhang).

However, 49 inches wont fit between the walls unless i cut into the
sheetrock on each side.

Any ideas? Do you think the previous owner actually cut the old vanity
top to make it fit?