I managed to fit one to my 1994 Celsior, again not easy but I did manage to do it including the remote boot release.
Another member with a 1994 UK spec model also bought one but the wiring was completely different even tracing back to the door switches so after several hours it was a no fit.
It is still in my garage, not mine so stays there.
The trunk release doesn’t need a relay as there is a factory one.
The remote keys were a bit flimsy with the rubber key ring bit splitting soon after purchase.