Jeff is correct: there are two versions out there. The C4 is the original assembly line version. Has a bit smaller diameter pins and the tail pin specifically is located more middle on the tail of the horse than the C8 version, which is located more forward towards the horse's hind quarters. If you end up using the C8 version, you'd have to remove the tail pin to use the existing holes in the fender. Bob Perkins has a set of C4's on eBay in the boxes (pricey) and the others you typically see are the later C8's. Most of the time, the sellers will post the back sides so you can see the numbers on the part itself. DO NOT go by the part numbers on the boxes, as they don't match the later C8's. Make sure you see both sides on the part itself before buying C4's, if that's what you want. Good ones are scarce, as Jim already mentioned. The rule I go by when I'm looking quickly, wanting to identify them is middle of the tail (pin position), C4, Top of the tail, C8.
