Saffs especially 2wd are a rare breed now as like been said most have been robbed of engine and box even im guilty of that.
They are on the up price wise and will continue BUT beware a lot have come onto the market claiming low miles and off the road for many years. The fact is if no paper history a 150k car in 2005 will today be flogged on as a 50k car. 90's mods and fresh paint usually gives this away.
End of the day its just a sierra that rots like any other ford.
Buy on condition not miles.