You can buy them new from a few places. I believe procomp makes them. Beware that you don't get a set of worn out ones if you buy used. You don't want them that look like mine. (pic in a minute).
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These are the procomps I used. They have a taper to them. I don't know yet if it will cause any problems so I can't vouch for them as a replacement besides saying they physically fit. They are for a newer superduty. Same basic housing.
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