camshaft valve cover chain skates or pads

Hi All:
Does anyone know what is the story about the skates or pads that the mechanical parts book (Tav. 5, Comando Distribuzione) show mounted in the cam cover? This is part number 161905 and is described as "Pattino Tenuta Catena". My car, which is a 1970 M-series Euro model, does not have evidence of this part ever being installed in the cam covers...there would be 2 attaching holes in the covers near the cam sprocket areas. I also do not see evidence of these pads in every photo I look at of the valve covers in my service books...you would see the heads of two domed nuts that hold the skate.

Does anyone have these skates mounted on their cam covers? The reason I ask is that both my cam covers do have evidence of the chains hitting the cam covers in the past...see attached photos. I have my engine out now and rebuilt with all new parts and so I am debating whether or not to add these skates because I do not want the timing chains to wear a hole into the cam covers.
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