There are a few different versions of power boxes, however the only thing you need to be aware of is that pre EGR and EGR engines require different versions of the box, so you need to establish if your engine has an EGR valve or not then check if you have the correct version of the box.
To fit you remove the connector from the FIP and replace it with the connector from the power box then plug the connector you removed from the FIP into the power box, this applies to all versions. Then there will be another small connector that goes to the MAP sensor, unplug the the existing connector, plug in the power box connector, plug the original connector into the power box. This for EGR versions.
Pre EGR it involves cutting the pressure pipe to the MAP and inserting a "T" piece and connecting the pipe from the power box.
There are other variations.
Not a good idea to use the wrong type of power box.