Hi guys , ok your are able to convert the old analog system using this new box of tricks , how ever its not cheap at £735.00 +vat fitting and programing is about £135.00 depending on your dearler and how quiet they are.
The part number is :LRO14222 , its for petrol and diesel models up to when they were fitted with the new system, THIS WILL NOT BE COVER BY WARRENTY, if your about to buy a range rover from a dealer , check to see if it works , if it dont get them to pay for one , or the deals off, type of thing.
Im not sure if you can get any thing cheaper from a radio speciltist, cheers all.