Paul, the old stuff you are dealing with is different obviously so you can put spares or repairs and people not bat an eyelid as they will know why, but try doing that on a 2007 ford ka etc and I reckon the punter might not be so understanding, so for most people selling cars they DO have to warranty it.

I bet a lot of small traders selling a cossie dont realise it does still come with an implied warranty if they dont specifically sell it as repairs only though!