Unless you're doing a lot of deep soupy mud I would not go with a greasable u-joint, especially the 5-153x which is for the driveshaft. The 5-153x has a grease zerk in its body with grease channels drilled through the body that weakens it. I'd go for the Spicer 5-1310x if you're talking about your driveshafts. Only if you're a regular deep soupy mud guy would I go for a greasable u-joint like current premium sealed u-joints like the triple-sealed 5-1310x which is stronger and more durable than what the factory installed.
If you're talking about the axle shaft u-joint I'd definitely only go for the triple sealed 5-760x. If you really really need a greaseable for the front axle shafts I'd go for the Spicer 5-3226x. Just know the 5-760 is a superb u-joint and was actually designed by Spicer for the then upcoming TJ Rubicon's front axle shafts. Jeep wanted a stronger and more durable u-joint for the Rubicon's axle shafts which is how the 5-760x came to be. The 5-760x and 1310x are up to 10X more durable (not 10X stronger) than their predecessors.
At one point all 6 of my driveshaft u-joints were greasable, what a frigging mistake. It was hard and a PITA to keep them all greased. I converted all to Spicer's latest more durable sealed series and never looked back.
