The drive flange seals become hard and inflexible with age, and will wear out if you drive through sand or mud.
They are easy to replace for a competent home mechanic adhering religiously to the instructions in the manual, but it is a fairly major job to remove the front drive shafts to get at them in the first place.
Read the manual first to see if you have the right tools, and if you decide to go ahead and do it yourself (I did last year) you might as well recondition the entire front end at the same time, as you will be pulling most of it apart anyway.
You'll be looking at new upper control arm bushes and suspension bushes for sure - as these wear out regularly. Other things to consider are wheel bearings and seals, ball joints (or just the rubbers), brake caliper seals and hoses (or maybe a 'big brake' kit), longer wheel studs if you are considering mag wheels, steering rack rubbers, tie-rod-ends (or just the rubbers), and a set of quality shock absorbers.
After all that you will need a wheel alignment. You can do that at home too if you have a level slab, but that's another story.
I bought all the parts first and it took me four full days to do the job, but I'm and old fart who takes half-an-hour to do a five minute job.
It sounds like a lot of work but after 30 years it will all need doing some day soon, and it's better to do it all once in your own time in your own shed, than break down miles away from home.
A quick word of advice - suppliers like JustKampers are NOT the cheapest supplier of quality parts. In fact, some of their parts are very expensive indeed, and not good quality at all. Tooley Imports in Sydney have supplied quality parts at good prices for nearly forty years, and if you place an order by 4 pm the parts will probably arrive the next day. VW Heritage in the UK sells OE parts at reasonable prices, and freight is usually free on larger orders. I bought some parts last week that arrived on my doorstep 4 days later! GoWesty and VanCafe have a good inventory, but freight can be a killer. Nick at Volksparts (Bungendore) is having a clean-out of new and used parts at the moment, and is always good for some advice. Mick Motors in Brisbane carries a reasonable range, but when dealing with Australian importers it always pays to ask the advice of the salesperson as to where the parts are made. They will sometimes carry to alternatives - cheap rubbish, and good quality.
Cheers, Roger.