Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
If length is ft (m) with numbers of 6600-6684 (84 buses) for 2003, what is the engine type?

### Inputs:
table_name: table, columns: ['Year', 'Make & Model', 'Length', 'Engine Type', 'Numbers']

### Response:
SELECT Engine Type FROM table WHERE Length = ft (m) AND Year = 2003 AND Numbers = 6600-6684 (84 buses)