Here's a link to a company specializing in clevis pins and retainers. There are some very interesting innovations. They also provide detailed dimensions. Roll over the product names to see pics. Click on the product names for detailed info and some videos of applications. Looks like you can pruchase directly but probably in bulk quantities.

http://www.pivotpins.com/catalog/catidx.html

No personal connection - just came across it and thought you might find it interesting.