I believe the wiring is in all diesels, yes. Certainly my facelift had no
FBH but does have wiring, and I know of others. The connectors didn't change, but where the wires go and what they are connected to did. It depends on the version of the
FBH which you can tell from a label on it.
The fuel tank piping is also present. You will want to remove the fuel pump too, and block off the feed pipe from the tank, and then the pipe from the pump at both ends (in case the new owner wants to fit one).
To fit the
FBH, one of the coolant pipes is cut short, so you will have to get an uncut one, but this should be the only pipe you need to replace. You will also need the coupling, which is basically a bit of pipe with some ridges in the ends. It will become pretty clear what I mean if you can get to see a car that hasn't had the
FBH fitted yet and compare it to yours. This all assumes that they weren't completely new pipes and routing for the later cars where it became an option, but certainly to fit a
FBH there was no new pipework, just cutting a section out of one already there, and incidentally handily marked where to cut!