I think this is a great little kit and forms a good basis for a GR3. I’ve just finished an old one (pre- the new re-release) and it’s come out pretty well.
From front to back:
Ditch the nose cone parts and replace with a GR3 LRMT thimble nose – I carved mine from balsa wood (yes, not resin!) and finished with putty. Add holes for the port side camera and the underside reaction control vent.
I added a pitot static tube using Master’s Hawk T1 tube – seems nearly identical to the Harriers (both made by Hawker around the same time?)
I opened up the nose gear doors and added some plastic card wheel bay with strip styrene details.
The intake door (upper 4 per side) need drilling out and replacing with card hanging down under gravity at different angles depending on whether the door is at the top or at the side. Those door cavities should also be boxed in internally – there’s no interconnection between the blow in cavities.
The one shape error that needs correction is adding putty to build up the fairing immediately behind the blow in doors, to remove the ‘pointy’ look and make it chunkier. Fair and sand to shape.
In the cockpit, I ditched the aft bulkhead with integral seat and replaced with card, some fuse wire pipe detail and a seat from Revell’s big Tornado. Instrument panel was sanded flat and drilled to represent instrument faces, other details added to fill it out. The HUD display of solid plastic was cut off and replaced with some clear plastic card and the HUD controls added, again by scratch building under the coaming. Card to fill in the gaping hole for the canopy to "move" within, and some detail to represent the actual scale railing.
Sand off the two big exhausts on the upper engine inspection door and add one smaller one starboard side, just upstream of the grill. (This is a change from GR1 to GR3 I think).
Add a RWR from card and fair into the forward fin. Use card to add height to the fin as the GR3 has a taller fin housing some new electronic guff.
Add a corresponding RWR aft on the tip of the tail cone and fair in. Open up some of the holes on the tail area, add internal baffle to the reaction control vent (aft, nose and wing upper and lower).
On the underside, I cracked the main landing gear doors open slightly, and shortened the airbrake about 6” in scale. (There a great set of videos on the web showing how to convert a GR3 back to GR1 standard here - https://www.youtube.com/watch?v=TMFNoumIFDE).
Fill in the resultant gap, add some rib detail on the airbrake well. I scabbed on a couple of plates to simulate the ALE-40(V)4 chaff and flare set aft of the brake.
On the wings, I dropped the flaps and ailerons, added in the fuel vent pipe from plastic rod (drilled out) and drilled out the reaction control vents at the tips, upper and lower, adding some deflector plate internal detail.
Finally, weapons: sand all the bumps off the gun pods and drill out vent holes. I drilled out the muzzle hole as well instead of the kit aerodynamic fairing.
Wing tanks need the fins removing - these got damage by debris early on in the Harrier’s life so were ditched.
If you’re making a Falklands fit Harrier, remove the 68mm SNEB pods and use either Sidewinders and rails or BL755 cluster bombs (I used the Wingman Models ones). You could have a go at scratch-building the big Royal Navy 2” rocket pods if you feel keen! If you want an RAFG machine, keep the SNEB’s and perhaps add a centre line pylon and scratch build the reconnaissance pod?
Add a couple of blade aerials behind the canopy and one under the LRMTS nose.
As you can see, to get a good representation of a GR3 (or for that matter a GR1) is just a case of a bit of scratch building, the old way. No resin, no etched stuff but very satisfying all the same.
Very useful source is the Haynes manual on the Harrier, great photos of GR3 in it.