I can only tell you my experience of this job and with the same droplinks you have.
As you have correctly summised, the sleeve has rusted through. Basically the droplink is a long bolt with a shank that is slightly thicker than the threaded part. Assembly consists of sliding on a cup washer against the shank, then a rubber bush, the sleeve, another bush, then the last washer and a nut. Its a sandwich essentially. However , when the sleeve rusts through, its a devil to remove the remains of the sleeve without an angle grinder and invariably the threaded part is already damaged, much weaker than it was when new and more liable to snap. This is why I suggest buying them as units and giving them a fighting chance by starting with fresh steel.
When I approached the job first time, I too just replaced the washers and bushes (local VW commercial outlet ordered them in for me). It worked for a while but a month or so after, the threaded part snapped and bottom washer and bush departed and are on the roadside somewhere. What a waste of time that was. I therefore ended up fitting units because I figured they were already 30 years old and rusty droplinks make bush fitting (especially uppermost ones) much harder. It was just simpler (and cheaper) to replace them complete and get it over with. When you tot up buying all those parts on their own (including droplinks which can be £50-ish each on their own some places) its a fair bit of money.
Fitting new droplinks isn't a complex job (more grunt and cussing) but you'll need to remove antirollbar. Getting droplinks on to the end of the antirollbar is a bit testing but once the job is done, you can pretty well forget them. Worth buying poly antirollbar mounts but I stuck with stock rubber droplink bushes as I don't like such a hard ride (personal preference).
Theres a knack to getting the droplinks on as I say. My internet is so slow tonight I'm unable to load youtube vids but I think this is what you need to know:
http://www.youtube.com/watch?v=7oXY68F8Uwo" onclick="window.open(this.href);return false; - if its the wrong link I'll correct it later.
Oh, and some say that the cup washers should face away from the bushes (ie not cupping them). I'm not quite convinced on this and it seems a bit of a water trap on the top ones if fitted like that. On mine they are the other way around (ie cupping bushes) - in common with other vehicles. My reasoning is that if they faced the other way, most of outer top surface of the bush would be doing nothing if its not in contact with anything (think about it) and the washers, once the nut is tightened up, are hard against the sleeve and do not and should not move about . Seems to perform fine anyway. I'll leave others to come up with a really plausible reason for having washers face away from bushes. I just don't see it personally. I did try it both ways.
Finally, you'll only really appreciate how bad the droplinks were when you replace them. Sharp corners especially put droplinks through their paces and when they're shot, the front behaves like a cosy armchair that has lost its firmness when leant over in a curve. The front will dip down on the outside corner making it unstable at times. When in good order, the antiroll bar can do its job properly and i'll handle more predictably when cornering rather than you (unconsciously) having to slow down just to negate even a moderately sharp turn. Its very much a progessive deterioration that you compensate for without actually realising until one of them breaks or it all starts clonking around.
If you try to just change bushes etc on old droplinks, they don't last long in my experience. They're often too weak after the rust has got in. You can cut off the threaded part and drill out and fit a long stud but I'd only do that in an emergency to be honest. Its more work than its worth.
The sleeves have gone for starters. Definately MOT failure. My place would fail that.
will order in the morn.
working for the next two weeks with only a day off so it wont be for a while.