A few people have been looking for their old clan skins recently.
I have found that Cookies Skin Bank has a large range of clan skins from the very early days of Kingpin. Clans like Mama, TCC, BEER, MDK etc. There are a total of 61 clan skin sets. Also at the bottom of the page there is a link to download them all in one pack.
If you want to go and have a look to see if your ones are there then just click here.
You will see in the menu 'Clan Skins' so just click on that to go to the clan skins page.
If you don't find what you are looking for there is a small clan skin collection at KP4Ever which you can check out here.