D prefix Marlin 1893's are always post WWI era. The Marlin company was sold to Rockwell Intl. during WWI, and after the War the company was resold to the Marlin Firearms Corporation. At that time serial numbers were restarted, and prefix letters added. These first post WWI guns were assembled from leftover pre-War parts, and so some 1893's with prefix letters are found after WWI. Your gun was most likely from around 1922-23 era. It may also have the "Marlin Firearms Corporation" rollstamp on the barrel.