The wipers on my 2003 TJ were noisy as well. 2 trips to the dealer and they couldn't fix it because once the Jeep was inside where they could work on it, they couldn't duplicate the noise.
I took the wiper motor gearbox apart and discovered no grease whatsoever. I greased it with a light synthetic grease and almost 4 years later, no noise at all.
The other thing the grease did was speed the wipers up considerably.
Vince