My 54" mower deck for the JD 345 will be completely refurbished in couple weeks. While waiting for that, I'm installing new bearings in the drive pulleys..#AM118794, replacing the #M111358 plastic bushings with brass oil sintered (full length) bushings in the #M143350 upper arm, and #M136635 lower arm . This will add greater protection and last longer than the plastic bushing. The #M78194 shaft the two arms pivot on was rusted so it was almost impossible to move them. So, I've decided to drill and tap and add grease zerts so I can grease this shaft. But, I've ran into a problem trying to drill the hole in the two arms for the zerts. I have tried about 18 1/4" drill bits and still cannot get a hole started. Those arms must be of some strong metal. Although, several years ago the #M143350 upper arm broke and I replace it. So, if it breaks easy, I should be able to t[drill the hole for the zert. I don't know why Deere didn't add zerts in these two arms as the phot below shows. Keep trying Fred, you might exceed.