Hi Jonathan,
Sorry I haven't gotten back to you. We do have 4" drop springs for your C10 available separately from the rears. The part# you are looking for is 19390F (
http://www.hotchkis.net/6772-c10-fro...l-springs.html). You definitely want to make sure that your springs and suspension components are matched so that you get the best performance possible. If you have any more questions please feel free to let us know.