Blue is what I would use. Use the Loctite primer or electraclean to clean and dry bolts and nuts for best results.

 

Thanks to everyone for your opinions/replies. For what its worth, I had my carb and transmission rebuilt at my local Harley dealer. Also had my engine remanufactured through them. The mechanic who did my work answered all of my questions while I was there and continues to be a great source of information for me. So on my way home yesterday, I called him. He says he uses red loctite on engine and transmission mounting bolts.