I thought I would pop this bit of info up in here as it may be useful for others in the future. I was unsuccessful in finding it in my time spent searching the forum database.
I am looking to replace my suspension bushes and I was looking through the SuperPro catalogue <
Find SuperPro Parts for My Vehicle >.
I noticed that for the D2 SuperPro list some of the bushes as a standard part number and some as for 'Extreme use only'. I wondered what the difference was - being for a 4WD could they be softer for flex, or harder?
A phone call to Fulcrum Suspension's (the head company) tech department and the difference is in the durometer rating of the bush (the hardness - see [ame="http://en.wikipedia.org/wiki/Shore_durometer"]Shore durometer - Wikipedia, the free encyclopedia[/ame] ). The standard bushes are usually a 70 rating. The extreme bushes are harder and are in the case of the D2, an 80 rating.
The rating of the Extreme use only bushes is identifiable in their part number, e.g.
standard bush - SPF2128K
Extreme use only - SPF2128-
80K
I imagine that most other Land Rovers also have the listing option for harder so thought this information may be useful for others in the future.