The Caterpillar 621F motor scraper replaced the 621E and was manufactured from 1993 to 2000. Units with the serial number prefix 4SK were produced in the U.S., and units with the 8PL serial number prefix were produced in Brazil.

The 621F came equipped with a 3406C engine, was turbocharged, and had an aftercooler. Improvements from the 621E model included pilot hydraulics and a new cab that lowered both vibration and sound levels.

Other than upgrades made to the engine beginning with serial number 4SK00370, the model was relatively unchanged during its eight-year production run. Over 1,300 units were produced. The 621F motor scraper was replaced by the 621G model in 2000.