There's also the Safe 2 Go people -- you can find out info on them at
http://www.safe2go.co.nz/. I have read that the reason carseats "expire" is that the plastic can deteriorate and become brittle with age, especially from sitting in a hot car, which can warp the plastic and cause it to break down at the molecular level. (A bit scientific for me!) Also, manufacturers tell us that the technology changes quite quickly, so even if the same model appears to be selling in shops, the technology may have changed over the past 10 years and the seat may have been improved/had the design changed, even though it still "looks" the same. At any rate, hopefully Plunket or Safe 2 Go can give you some advice. Good luck, and do let us know how it turns out!