I`ve changed a few on an XK8 for a friend recently. If doing the work yourself, then a hydraulic bench press, bush removal/replacement mandrel kit and a good range of sockets is almost a mandatory requirement. Old bushes can really stick in the various housings and can require a good heavy push to get them moving. If fitting new OE grade bushes, similar kit is required to fit new bushes to pre used wishbones. Such work is not for the faint hearted. One has to tear out the suspension in stages which is not so easy on hands and knees. A lift or ramp eases the physical toll. Having salvaged a used wishbone or other component, there is a fair amount of grunt needed to extract and replace bushes. Then you have to fit the parts and reset for suspension alignment each and every time you change a number of bushes. Be warned. The work is arduous, dirty, time consuming and on occasions frustrating.
You have a choice of bushings. OE grade or after market poly types. My experience is with Powerflex bushes fitted to my S-type. These are available in slightly uprated Purple Series which are good for normal road use or there are much resilient Black Series which give an much harder ride, precision steering, cornering and braking response. Only use Black Series if you want a competition like ride which at slow speeds can have passengers loosing their dentures. Purple Series are great for a normally used car and will not over stress mounting points on the car or require additional bracing or special mounting point lock up devices to be installed.
The most competitive prices for Powerflex poly bushes are from Upratedbushshop.co.uk. You order the parts as you wish on an individual basis. Note there is a lead time of about ten days from the moment you order. The service from Upratedbushshop is excellent. You will sometimes hear adverse reports of poly type bushes collapsing over time. Most of this bad press comes from early materials which fall far short of the types now offered. Powerflex offer a lifetime guarantee for their products. Fitting Powerflex bushes is far easier than fitting steel tubed OE bushes. Powerflex are almost hand fit using a small amount of liquid soap. Note please, I have no connection with the company other than that I have live experience of fitting their products to my own S-type. The story of my bush installation and conversion is here.
http://www.jec.org.uk/forums/viewtopic.php?f=200&t=8040
In time all bushes may need replacement. What you initially need to replace should be on an as immediately required basis with later work being done as resources allow. replacing some parts is a good way to begin but the new bushes soon show up old part wear in adjacent components. In my experience, one thing leads to another. In my case, I gradually replaced four anti-roll bar bushes, ten bushes on the rear suspension, two rear tie rods, eight front suspension bushes, two front ball joints, two front wheel bearings, four ARB links, four gas dampers and one complete new upper rear wishbone. That little lot set me back a couple of thousand pounds. My labour amounted to about 130 hours.
Mike K