On L-5 Colony in the year After Colony 194, Long Mei Lan, wife of Chang Wufei, piloted a Tallgeese of her own. This was not the same suit as the Tallgeese we know today because it was destroyed in battle and her with it. Her nickname was Nataku, a lengendary warrior in the Long Clans, and Wufei honors her by calling his Shenlong by the same name. Where did this come from you ask? My theory is that Master O who took part in the original Tallgeese project had the blueprints and built it to defend the L-5 Colony until the Shenlong was completed. This is probably the truth, but since no official documents were ever published on the matter it cannot be considered 100% fact.
During the end of the Gundam Wing series a new Tallgeese model arrived on the scene. The Tallgeese II shared the same abilities as its predecessor, but not its looks. We do not know when this suit was made, but I think that Treize built it after he realized that he would not be able to control the Epyon. He had the blueprints from the original Tallgeese and duplicated its abilities perfectly.
In the year After Colony 196 the Tallgeese III arrived on the scene piloted by Agent Wing of the Preventers (a.k.a. Zechs Merquise). To this day we do not know the party responsible for building it or when exactly it was built. It is safe to say that it was built after the Eve Wars between the White Fang and the Earth Sphere Alliance. My guess is that Zechs had Howard secretly help him make it by giving him the materials and he built it himself.