have a look at your ecu, if you have the older type, with the 40 pin connector (you will have to look inside) the connector is a series of soldered over holes, 2 x rows of 20, you can swap these ecu's around, any 40 pin ecu should work on any other 40 pin ecu car, even the ones with early nats, however the later ecu's, normally easy to tell externally, as the lid is held on with 4 screws on the top, internally, it will not have 2 x 40 pin slot, it will have a slot of 20 and one of 30, these ecu's must be coded to the correct car and nats key.
be wary using a different ecu, the maps are not always great