I am looking to purchase an LR3. I am a DiscoII convert. The interior space makes this large American happy. Can the navigation system be added at a later date? Can the rear locking mechanism also be added later? I am looking at a truck without either, and I may want them both down the line. I think that the rear lock should be easy to install, but I am worried that the nonHD trucks are not equipped. Also, are these trucks more reliable than their predecessor? I took the 2 in for a service engine light exactly 1 week ago and the light is back on. I traveled 300miles one way for this service, so needless to say I am not very thrilled.