Who carries the majority of parts for the LR3? Which one is the best value for your money? I am looking for the thermostat housing on the V6 that has at least three tubes coming out of it at the bottom. I also need the coolant recovery tank.

 

Amazon has a bit, rock auto, lucky8, rovahfarm doesn't stock much, but he can get stuff, rovers north, Atlantic British.

For OE parts, http://landrovermerriamparts.com has very good prices, usually better than the big rover houses, for OE, green oval labeled parts.

 

I've had very good luck with Land Rover Parts & Rover Accessories From Atlantic British | Discovery, Range Rover, LR3, LR2, Defender, Freelander and Land Rover Series Parts & Accessories

 

A lot will come up on Ebay.
For used, www.car-parts.com
I am a new owner and people warned me, "Parts are expensive", Parts are too hard to get".
There are a lot of sources for parts and random comparison of different searches, such as: fuel system, suspension, etc. shows that a lot of parts are cheaper than the comparable parts for my Chevy Silverado.