Both Harrier airframes remain in existence.
XV741 spent many years with the Naval Flight Deck school but was sold to the civil sector within the last two years. The RAF disposal team had no regard for its historical significance. The scrap metal value is all that these people care about. I believe the airframe went to Bentwaters and will be preserved.
XV744 was the airframe decaying outside at MoD Shrivenham for a long time. It is now on external display at Tangmere Aviation Museum having been loaned (rather then sold) is my understanding. It was in very poor shape and the RAF could do a lot worse that donate the airframe to Tangmere. Unfortunately Tangmere has limited space under cover, hence long term security is not a given.
The RAF Museum at Cosford does not have a GR3. If someone had some foresight; XV741 would have gone there. Now that that opportunity has gone, perhaps the GR3 owned by RAF Cosford could at least represent the type at Cosford. Again short sighted military opinion would say that Cosford has a Harrier. They do, a GR9. But that is like saying that a first generation Mini is the same as the latest Cooper, when clearly all that is in common is a name.