A WW1 production 1911 nearly always had wood grips from the factory, though not all had diamonds-there were variations. That frame would have served in WW1, then returned to an Army arsenal for storage. When WW2 began, they took all the stored guns apart, threw the frames in one pile, and the slides and barrels in another. They tossed all the wood grips in the trash, replaced any rusted out or excessively worn parts with either new production or used parts that passed inspection, reassembled the guns, then parked them and slapped new plastic panels on them.
This process was repeated after WW2, Korea, and Vietnam. Some guns got reworked multiple times. Yours is exactly how a GI from any war after WW1 would have received the gun and fought with it.
