D6, I zerked my 2wd last year. I bought self-tapping zerks from Napa and drilled through the cap of each joint. I did the tie rod ends and upper ball joints plus I think one of the steering linkage joints. The inner ball joints are a PITA, I did one on one side but not the other because it was too tough to get my drill in there.
When drilling add some grease to your tip to catch debris as you drill. Also, only go deep enough to drill your hole and no further. There is not a lot of "air space" between the cap and internal parts. The caps are thicker than they appear.
For some reason mine will only take a tiny squirt of grease in the tie rod ends before it acts full and it hydraulically locks up all movement. . . cannot twist it by hand. So I only add a squirt here every 5-10K miles.
I never got the nerve to do the lower ball joints since they are cast and I wasn't sure where to drill.
Vaughn