So the back pad has 4 fasteners-a 6x25 phillips headed screw, with an aluminum (?) ferule-at least on my 70, 74, and 75 -4 cars.. My 914-6 has the proper screw, well at least it's a 6x25, but instead of the ferule, it's a very proper lookng black plaster washer, short of, a bit pyramided, if that make sense. What is accurate? I have a set of the aluminum ferules in my collection of parts. Really appreciate it. Thanks BW

The aluminum ferrules are proper for the car. They tend to corrode away over time from water ingress so if you have good ones you are luck, that is what came on the car.

I've restored several 914-6s and all had this part in aluminum. Perhaps they went to plastic on the later cars (not sure). Original 914-6 shown below

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Thank you, I have a dozen or so, from parts cars. I'll see if I have a good set. Appreciate the info. BW