user: Question: What manufacturer has a wheel arrangement of 4-6-6-4, and a Class of Z-7?
Columns: ['Class', 'Wheel arrangement', 'Fleet number(s)', 'Manufacturer', 'Serial numbers', 'Year made', 'Quantity made', 'Quantity preserved']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Mallet and Simple Articulated Locomotives', 'Mallet and Simple Articulated Locomotives', 'Mallet and Simple Articulated Locomotives', 'Mallet and Simple Articulated Locomotives', 'Mallet and Simple Articulated Locomotives', 'Mallet and Simple Articulated Locomotives', 'Mallet and Simple Articulated Locomotives', 'Mallet and Simple Articulated Locomotives']
SQL:

assistant: SELECT "Manufacturer" FROM "Table" WHERE "Wheel arrangement" = '4-6-6-4' AND "Class" = 'Z-7';