I've read about draining the oil (if used) from the swivel pin housings and using grease, which sounds like a better idea to me. Problem is, I think I've found the fill plug (square plug at about 2 o'clock in the photo?) but how do you drain them? Is there a drain plug in this photo that I'm missing?

 

Later D1s like yours did not have them. There would be two more fitting below the fill hole, further down the housing. You can purchase a small fluid pump to suck out the juice remaining, Home Depot carries it in the lawn mower parts aisle (good for oils, tranny fluid, etc.). If going grease, cut wheels to inside all the way, it makes a straight shot for the grease to get to the bottom. Some people mix grease and oil (home made pudding), some people use Lucas Red & Tacky #2 grease, about a whole tube per side; the factory spec is more like "00" oil/grease from lawn mower store. There have been right ups of nifty injector system that uses a plastic hose b-a-r-b, some tubing, and syringe like item to squeeze in the desired substance.

 

#1 and #2 greases are too solid for cv joints, they won't get proper lubrication.

 

Wouldn't a non-drain equipped swivel housing already have been filled with grease? I mean, isn't the reason they deleted the drains because they switched to grease to prevent leaks?

I believe the pictured swivel housings are filled with grease, but the seals have failed and some of the oil has separated from the grease and seeped out. The CV joints are probably still lubricated, and you could just top them off with an ounce or two, but it will continue to weep.

You can crank your steering wheel all the way over to the side, remove the fill cap on the hub that is open from the front of the car, and stick a dip stick past the swivel ball inside the housing and check what you have in there if it is oil or grease.

If it is grease, the only way to change it out is to pull the housing. I have seen a write-up on a way to change the seal without pulling the housing by cutting the rubber seal and unscrewing the metal spring from itself, slipping the seal in place and re-attaching the seal spring. I wouldn't do it that way myself though but is has proven to work.

The grease used is CV joint grease which is thinner than bearing grease. It can also be mixed with gear oil to thin it even further which may be useful for those who have drains. I used straight CV grease in tubes from CRC (it took 8 tubes) but if you search you can find Land Rover vendors selling the grease in one-shot tubes for a good price.

 

Well, if there is grease, or 00 grease in there, you could probaly thin it more with something cheap, and still slurp most of it out with a pump. However, the preferred liquid seems to be the 00 grease, which is very close to home made pudding (gear grease and gear oil, mixed together by those too busy fixing something else to attend to swivel gaskets). And then there are those who put in the heavier grease, to quiet the already noisy CV joints while wait for some extra overtime pay to put toward that, or an unsuspecting potential new owner (something else to examine on a too-good-2-B-true Disco deal). I heard the faintest tick from one of mine, put the Red & Tacky in there, mixed with what oil was left, noise is gone, but I pulled a CV with half axle at salvage for $35 to add to my spares pile. I'm am sure the noise will return. By the way, the cavity inside the swivel housing is large, like about a softball.