The Cascavel 1 (Rattlesnake), was the first production model developed from the prototype MB-1 Cascavel-37.  It was produced in conjunction with the EE-11 Urutu APC and followed by the similar EE-3 Jararaca Scout Car.  The main visible change from the prototype was the replacement of the modified M8 Greyhound open topped turret by the complete turret assembly from excess US M3 light tanks. 16 of the first pre-production set were completed, followed by an additional 50 with improved transmission and other mechanical updates. The vehicles are generally indistinguishable externally. The Cascavel 1 was only used by the Brazilian Army with most vehicles being eventually converted to Cascavel 2 standards.

Total production of all Cascavel versions (Marks 1-5) reached 1,738 units built.  They are divided as follows: Bolivia (24), Brazil (409), Chad (? captured from Libya), Chile (106), Colombia (128), Cyprus (124), Equador (32), Gabon (12), Iraq (364), Iran (? captured from Iraq), Libya (400), Paraguay (28), Qatar (20), Suriname (6), Togo (10), Uruguay (15), and Zimbabwe (90).