I got my injectors and return line kit from Classic Diesel Designs. Theirs isn't a rail, but a much better than original and auto parts stores, ebay, etc. I installed mine about 2 1/2 years ago and no leaks so far. and doing other things, like replacing the injectors once with auto parts ones that quickly failed and then with ones from CDD, the caps, lines, rings, etc., went right back in place with zero issues. I also got their filter return line kit delete. My injectors have also been great, as well as the pump and a few other items I got from them, no issues and truck is running the best it has since I made the changes. They also have great tech support and have helped me through several issues, even on things that didn't pertain to parts I bought from them. I can't compare R&D as that wasn't the route I went but have heard good things about them.