Ok so i went to pick my truck up at the shop this morning, and crawled under to do my inspection and noticed the output shaft seal on the tcase was leaking. I asked them to replace it and they did. That was the second new one i had changed it once before, and im positive its not the slip yoke. Any ideas on what it is? 02 duramax 4x4 manual transfer case. Only 300 miles since the tcase was rebuilt.