I've got this same issue with my front driveshaft...can you tell me if the part numbers for the front shaft are the same? Thank you for posting this, it saved me a ton of time and probably money trying to diagnose my leak....I sent some photos to AA, and they confirmed this was most likely my problem. It's dry around the actual output shaft, the oil seems to be coming from inside the yoke, which didn't make sense until I read this...Now I've got a good idea of what's going on and why!
I just noticed how old this thread was. Hopefully some of you folks are still around and will notice this. I looked on the AA site to see if they give the part numbers for the front nut and washer, and they don't. I'm assuming it's different, since the shaft size is different. Worth a try!