i have a 68 rs and having problems with tail lights. the running lights and signal lights will work individually but not together. i have replaced socket assemblies from classic camaro a few years ago and i am not pleased with the quality. could this be the problem? what is the quality of replacements from american autowire?

Amercian Autowire is almost the standard now as far as complete wiring kits go. I've used them on my last 3 cars and have no reason to change to anybody else. Great product.
Your problem almost sounds more like a grounding issue.

Make sure you are using the right tail light bulbs.