1939 Graco Products Performance Meter Motor Diagnostic Unit Untested RARE! See photos for details and feel free to ask any questions you may have as I am here to help! The 1939 Graco Products Performance Meter Motor Diagnostic Unit is a rare and vintage tool designed for diagnosing motors. This unit serves as a unique and collectible piece for car enthusiasts or those interested in automotive history. With its specific year of publication, this diagnostic unit offers a glimpse into the past and may hold value for collectors or enthusiasts looking to add a piece of automotive history to their collection.