Successfully complete the indicated task to unlock the 
corresponding truck:

Avenger: Get first place in all events. 
Blacksmith: Get 50,000 Monster Points. 
Destroyer: Get 10,000 Monster Points. 
El Toro Loco: Get 70,000 Monster Points. 
Grave Digger 25th Anniversary: Win Las Vegas. 
Iron Outlaw: Get first place in all events. 
Monster Mutt Dalmation: Get first place in all events. 
Pastrana 199: Get first place in all events. 
Suzuki: Get 110,000 Monster Points.