Hello Michael, thank you for your interest.
Not sure what more I can add, other than I'm looking at NE Europe 1944-45 time frame. According to the August 1943 War Establishment, each infantry battalion should have it's own support company. It is here where is found the 3" mortar carrier platoon, and would contain 7 vehicles, according to this pdf file:
http://www.warestablishments.net/Can...ust%201943.pdf
Other than that, any info that can be added would go towards the building of a 1/35 scale model.
regards,
Jack