Quickly use the crane to get your partner up, but look for three pieces of track and place them on the track then get two boxes and assemble them. At the end of the level, carry an anvil while the boxer punches you. Destroy each truck that comes in with the plane's guns for the parts to build the anvils. After defeating the waves of soldiers, get into the truck with the ark and ram into Belloq's car.
Note: There is a Soldier in Belloq's car. I call him Unnamed German Soldier.