Most u joints have zerks in the crosses, the extreme duty joints I use have a solid cross and needle zerks in the caps, some have none.

Access would depend on what mounts and housing you have, I merely have to remove half of the drive line cover to get to mine, three points are a different story, you normally have a hand hole on those. I recommend greasing the joints at the beginning and end of the season, mostly to displace moisture....

Good luck.