You could reach out to Andreas Rhude. thompsonboat@msn.com
He shows up on this forum from time to time but not recently. He helped me to date my cartopper.
Around 1938 the artwork in the catalog changed to reflect spaces between the half ribs like yours has. Prior to that half ribs showed as butted to the ribs with no spaces.
While it’s not totally definitive it can be used as a guideline to date yours post 1938.