That is how my 1990 Lexus LS400 was before I installed OEM Toyota/Lexus struts on the rear. About 6 months ago- the previous (an original) owner had "KYB" high performance struts installed. I could feel the rear suspension picking up every bump and the rear was difficult to press down. I actually like a soft ride and I knew this was not how the LS400 was supposed to be. I remember riding in my aunts 90 LS400, and it has a "floaty" ride, but I am guessing her shocks are getting worn. I have seen several LS400s, with floaty, super soft suspension. They are supposed to be somewhat soft and floaty on the LS400. I had the KYBs removed and had the Toyota struts installed in order to get the ride like the car had when it was new. The car has a much softer ride now. The suspension takes the large bumps with ease and you can hardly even feel them. I am really pleased now with my suspension.
I was very impressed with soft ride that the 84 300SD I test drove a few weeks ago. It was very soft and soaked up all bumps, but I am assuming the struts are a little worn.

Sounds like you saved a little money doing the change yourself. Did the rear seat have to be removed? I know that on most Toyotas (probably most Japanese cars), that the rear seats and sometimes rear package shelves have to be removed in order to change the rear struts. I had to pay $90.00 to get mine changed.

I've been told that KYB shocks are very stiff. Some folk like them, we will see since I got a set for the front of the 280 SE for cheap on eBay. If I don't like them, the originals go back in.

I also bought a set of used shocks for the rear. Unless they are completely gone, the will be better than the Monroe Gasmatics (or whatever) that are back there. Too much gas pressure (the rear sits up too high) and so stiff you'd think they were solid.

Peter

I prefer the stiffer ride as i like to drive fairly aggressively and 'throw my cars around' a bit (within reason!:-) I know for this i should probably be driving a VW golf and not a Merc, but I'm not a 'boy-racer' as we say back in the UK.
I do like my cars to have good solid handling and my old Peugeot had good suspension (for French farm roads i'm told) so i'm used to the firm feel.

Rear seats didn't have to come out, thankfully, just the trunk liner on each side needed to be pulled back. Not a difficult job- took me 4 hours as it was my first time ever and the bloody nuts were being stubborn coming off.

The car doesn't wallow like a big whale going over hilly country roads now:-)

Subframe Mounts
 

There was a mention a number of posts in this thread back about not being able to do the subframe mounts. You might want to do a search, read some of the threads and decide if you can or can't. If I recall correctly, there are ways for a DIYer to do that job, given fabrication of some special tools, care with certain phases of the job, and time and patience. If you enjoy doing your own work, check it out before you make a decision. Just make sure you make an informed and careful decision.

Here is a good one by Cornblatt:

http://www.peachparts.com/shopforum/showthread.php?threadid=76569#post485053

Haasman

I have heard most folks say that. I know that the ones that were on the rear of my car were very stiff. It was like my rear suspension was metal to metal. The factory Toyota-Lexus struts really made a difference. The interesting thing is that KYB makes some struts for Toyota-Lexus, but they are much softer than the strut sold under their name. There is another maker for the struts for Toyota. I think it is Tokito or something like that.