difficult grease nipple on uni joint

[RobboMC Junior Member Find all posts View Profile Close RobboMC]

The grease nipple on the first universal in the rear drive shaft points towards the driveshaft bolt
and is not accessable. I tried everything on the weekend. I can't turn the nipple and (of course)
the bolt rotates with the shaft and joint.
Has anyone had a similar isse and what's your solution?

I thought of removing the nut and seeing if that allowed enough clearance, but the bolt
seems to be welded to the output flange so that seems immovable.

Removing the whole driveshaft just to fill with grease seems like overkill but I will if I have to as leaving
a dry universal is inviting disaster.

By the way, what grease do you guys use in these joints?