The original purpose for this book was to supply replacement volume control and capacitor part numbers... However.. It is a great index to Riders, and provides a column for number of tubes, AND it provides the tube complement! If you do not know the model number of a radio, look up the manufacturer and scan down the columns for your number and types of tubes.. You will get the possible models along with the Riders locations for schematics.. This book is the singularly most under-rated book I know of.. Often it sells for $5.. Get as late a copy as possible to include as many sets as possible!