The use of a newly developed light alloy, DTD 646, allowed strengthening of the Mk X structure without much need for redesign. The gross weight was increased by 2,000 lbs. Externally the Mk X differed from the Mk III with longer carburettor intakes and larger spinners over Rotol propeller hubs. Some Mk Xs used de Havilland propellers with smaller hubs. Beam guns and large tailplanes were fitted. (Don’t know if the Trumpeter Mk III has the broad chord tailplanes – if not try A2Zee models http://www.a2zeemodels.co.uk/wellington-tailplane-4617-p.asp ). Cabin and starboard nose windows fully enclosed. Rear gun turret initially FN20A, FN120 or FN121 units fitted to later aircraft. New radio and navigational equipment resulted in aerial installation changes or additions. During production a new rudder and elevator with different shape horn balance introduced. Twin windscreen wipers fitted. More efficient heating system installed resulting in both exhausts being fitted with barbed flame dampers.