Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_54316 ( "PRR Class" text, "Builder\u2019s Model" text, "Build date" text, "Total produced" real, "Wheel arrangement" text, "Service" text, "Power output" text )

### Question ###
How many total units were built of Model ds-4-4-660 with a b-b wheel arrangement and a PRR Class of bs6?

### Accurate SQL ###

SELECT SUM("Total produced") FROM table_54316 WHERE "Wheel arrangement" = 'b-b' AND "PRR Class" = 'bs6' AND "Builder\u2019s Model" = 'ds-4-4-660'