Verified answer

It is custom to express Length first, then Width, then Thickness.

Units of Measurement   Feet and Inches  Abbreviation =

The IEEE standard symbol for a foot is "ft". In some cases, the foot is denoted by a prime, often approximated by an apostrophe, and the inch by a double prime; for example, 2 feet 4 inches is sometimes denoted as 2′ 4″.

Your numbers are in FEET.

103.2 Feet long, 79.8 Feet wide 19.9 Feet thick.

usually the longest is L, 79.8 would be W, making 19.9 as the thickness ("height") ... but it depends on perspective,  {Think a book standing up, facing you vs spine facing you vs book laying down in various positions.}

if this is to be a "box " then any two will work , with the last one being the ' height '