My M-1 Garand has the Korean War vintage trigger guard, like yours. Mine has a Springfield receiver and IIRC a Harrington & Richardson trigger group. Mine has a cartouche in the stock which indicates that it was rebuilt in San Antonio.
I'm pretty sure the style of trigger guard you are referring to is the stamped type vs the milled type. The stamped guard started being used on the Garand in late 1943 or early 44 and predates the Korean conflict.