Simplify the following text for a Grade 4 native English-speaking person.
Original: It is a successor to the famous World War II ` Jeep ' vehicle by way of the Willys civilian Jeep ( CJ ) in the 1950s , later produced by Kaiser-Jeep and by American Motors ( AMC ) .
Simplified: It replaced the Jeep CJ which came from the World War II Jeep , or Willys MB .