This paper model is a SD T19 half-track Howitzer Motor Carriage (HMC), a mobile tank-destroyer based on the White M3 Halftrack with a mounted 105mm howitzer, the papercraft created by vladcorail. The gun and its shield were mounted in the cargo space of the halftrack, positioned to fire forward over the drivers compartment. The windshield area and windshield cover were modified to enable the gun to project to the front.
A total of 324 of the T19 Howitzer Motor Carriage were reported manufactured by Diamond T in 1942. The T19 HMC was used until mid-1945 after which it was considered obsolete. Some of the T19s were converted to M3A1 Halftracks in mid-1945.
You can download this papercraft model here: WWII SD T19 Howitzer Motor Carriage (HMC) Free Paper Model Download