Ithica 37

[Redstick]

What can y'all tell me about the difference in the trench and riot mod. 37's? Is it just the length of the barrel? How 'bout a place I could find a date by serialization? Any other info would be appreciated.
Thank you,
Redstick

[mtnboomer]

Trench models wore the heat shield with a bayonet lug, riot models had no heat shield.