The "fat" front part of the trigger guard and frame were fabricated as a single, solid piece (Item 34 in the parts list shown above or Item 90-29 in the parts list shown in Brophy's book about Marlin firearms). The trigger guard is attached to that "fat" part with two pins. It is not part of the safety mechanism. The safety button is located on the top tang of the frame and is operated with one's thumb. With all of it's complexity, the model 90 frame was obviously an expensive part to make.