I'll still try to post a picture.
Strange, but I see no evidence of any modifications to the underside. The drawbar/truck and spring are all held in place with a single rivet. The rivet looks totally original.
Maybe I got an abberation in production? Often, in the firearms world, especially in the years after WWII, when a new model of a gun was brought out, they often blended spare parts from the old model, until those spare parts were all gone, and then they switched over to the newly designed parts.