Two "flat pieces" is not overly descriptive but I am going to guess it is the Series 80 firing pin block actuating assembley.
If in fact this is what they are they install on the right side of the frame. The piece with the two holes in it and the long narrow nose is what lifts the firing pin plunger.(FP lock lever) The long nose points to the front of the pistol and when fitted correctly it sits flush with the top of the frame. It only rises above the frame when the trigger is depressed. It is fixed in place by the hammer pin.
The other piece is the dogleg one with one hole(Trigger bar lever). It is fitted with the long leg pointing down and resting against the rear of the trigger bow. It is retained by the hammer pin.
The way it works is thus- When the trigger is depressed the trigger bar lever is moved rearward by the trigger bow. As it moves rearward the short leg of it interacts with the Firing pin lock lever and lifts the nose of it upward, depressing the firing pin plunger in the slide, allowing the firing pin to travel forward and strike the primer.