UJ's were a regular fail on "old cars" back in the day and the noise is unmistakeable. Like a high frequency pneumatic drill, a sort of dull grinding noise. Often UJ's live exposed to the road, and some I changed had dried out completely, the rollers were totally rusted and ground away.
These days, I think technology has improved. The grease which is visible in Morgan UJ's is a sort of luminous green. Certainly on the Trads, the front UJ is so enclosed that it's tough to access. The rear, although "exposed" is well covered by the rear axle cavity, and stays clean anyway.
There are two things to consider. Too much grease will lift the rubber seals. And it will centrifuge around the transmission tunnel creating a greasy mess. So like most things Morgan. Judgement call. There's no right answer. The UJ's need grease, but they don't need much. Similarly with the sliding yoke. It doesn't need much. Factor in low mileage and they should last for years anyway.
