as far as which is better, there's a long-standing feud in the p38 forum (search, it's the most prolific topic I think, many threads....) some call coil conversions castration, some call them an improvement. I won't get into that and I can't comment on the ride in a MkIII as I've never been in a converted one.
As far as a US dealer, I have rebuilt airsprings for 1/2 the cost of OEM new, OEM new airsprings and coil conversion kits.
http://www.rover-renovations.com/Range-Rover-Air-Springs-s/265.htm
As far as a US dealer, I have rebuilt airsprings for 1/2 the cost of OEM new, OEM new airsprings and coil conversion kits.
http://www.rover-renovations.com/Range-Rover-Air-Springs-s/265.htm