John
I replaced the rear springs on my 08 +4 just over a year ago. I chose, following advice from Peter Mulberry of Mulfab, and because I am no lightweight to fit 4 seat springs to my 2 seater so they were a little harder to fit because of the spring 'set'
There is no way round it, its hard work and 2 pairs of hands make the job much easier, in fact almost essential unless you are going to make up some tooling. However its nothing technical, its all 'nuts and bolts' work and easily achievable if you take care and work steadily. It would fill the pages here to rewrite the process but even though I have issues with a lot of statements on GoMog (and I say that having written quite a lot that was later put on under the webmasters name!) it is correct when it says that having someone stand on the front of the spring to get the eye down to the shackle plate at the front makes it simpler, its not as scary as its made out to be but of course you need to exercise care when working with anything that stores energy the way a spring does. If you tackle it you can always send me a PM and I will e-talk you through the process to save boring others.
As for sourcing I think genuine MMC ones ordered through a dealer is the best option, there are rumours put around about them being sourced from India but someone who is a friend of the supplier to MMC told me they are made in Coventry but they will not sell direct. If you decide to go for 4 seater rear springs it will raise the rear of a 2 seater about 15-20mm higher tyhan a standard 2 seat car and then it will settle to about the height of a new car so nothing dramatic but it gives a superb ride as the spring rate is the same (set gives the height and rate gives the comfort/compliance level with leaf springs).
