Here's the sitch:

Hesston/Fiat 160-90 MFWD tractor.

The front axle has two u-joints at the wheel end of each side of the axle.

The U-joints have no zerks on them whatsoever.

The book says nothing about pulling them off and packing them. There aren't any plugs/holes into which I could put a zerk on the u-joints. The rubber seal protectors are coming off the crosses on the u-joints.

What's other folks' experience in this type of case? Pull the axles to get at the u-joints and pack them by hand? Wait until they fail and then just put on new ones?