I dont get why people are ignoring my replies, I have done this conversion, not in the escort but in the fiesta and so it is going to be pretty much exacly the same, and its is also an N reg, so doubt it is going to be any different.

If you get a deep, desk or dewy ecu you can keep your old key and not have to change the transponder thing. I wouldnt risk using an ecu from a black top as the pin setup for the ecu may be different, and as the blacktop is a different engine to the silver top i wouldnt recomend using it. The mk1 and mk2 silvertops have a variety of different ecu's, some internal, some external. Just because you get an ecu from a mk2 doesnt mean it will work, and just because that didnt work doesnt mean that the one from a mk1 will work.

So to irriterate, you need a deep, desk or dewy ecu, and these might be in a mk1 or mk2.