1966 Driveshaft - Which End is Front?

One more thing about these u-joints. They have a single flush mount grease fitting installed in one of the caps. Call me a newbie, but I've never seen a flush mount grease fitting before. Had to do some googling to learn what that's all about. I guess I need a needle adapter, like this, to grease them. Tried replacing them with a standard zerk fitting, but the threads are smaller.