The only other one not to sign was Martyn Dunne, High Commissioner to Canberra who is not a career diplomat, having worked much of his life in the army before heading up the Customs Department.
Mr McCully said the $9.2 million was from a budget of $398 million.
The letter was sent to Mr Allen on March 15 ahead of an unprecedented meeting of all heads of mission that was to have been held in early April but has been delayed.
It says the New Zealand Ministry of Foreign Affairs had earned an international reputation "as one of the most effective smaller country diplomatic services in the world. We are deeply concerned that the proposals for a new Mfat business model would undermine or even destroy these strengths at a time when we need more than ever to sharpen our international edge."
Mr McCully sought to distance himself from some of the proposed changes last week in an open letter he sent to Mr Allen, and reiterated that he had been given too little time to see the proposals before they went out for consultation.
He said yesterday Mr Allen had not been embarrassed by the letter and had asked him to release the letter publicly.
The original proposed changes would have saved about $25 million a year.
About 600 staff were to have been forced to reapply for their jobs and 300 jobs cut altogether, with more outsourcing for non-diplomatic overseas jobs, cuts in allowances for spouses and children in overseas postings, appointments on merit and not seniority, and diplomats encouraged to specialise rather than be generalists.
DIPLOMATIC BAG
NON-SIGNATORIES
Mike Moore, Washington; Jim McLay, United Nations; Mark Blumsky, Niue; Martyn Dunne, Canberra
SIGNATORIES
AMERICAS
Jeff McAlister, Brasilia; Daryl Dunn, Buenos Aires; John Mataira, LA consul; Christine Bogle, Mexico; Andrew Needs, Ottawa; Rosemary Paterson, Santiago
ASIA
Bede Corry, Bangkok; Carl Worker, Beijing; Heather Riddell, Hanoi; Robert Kaiwai, Hong Kong Consul; David Taylor, Jakarta; David Pine, Kuala Lumpur; Reuben Levermore, Manila; Jan Henderson, New Delhi; Michael Swain, Shanghai; Stephen Payton, Taipei; Patrick Rata, Seoul; Peter Hamilton, Singapore; Ian Kennedy, Tokyo
EUROPE
Peter Rider, Berlin; Vangelis Vitalis, Brussels; John Adank, WTO; Dell Higgie, UN/ Geneva; Derek Leask, London; Rob Moore-Jones, Madrid; Ian Hill, Moscow; Rosemary Banks, Paris; Trevor Matheson, Rome; Barbara Bridge, Stockholm; George Troup, The Hague; Philip Griffiths, Vienna; Nik Kiddle (Charge d'Affair) Warsaw
MIDDLE EAST AND AFRICA
Malcolm Millar, Abu Dhabi; Taha Macpherson, Ankara; David Strachan, Cairo; Justin Fepuleai, Kabul; Georgina Roberts, Pretroia; Rodney Harris, Riyadh; Brian Sanders, Tehran
PACIFIC
Nick Hurley Apia; Mark Ramsden, Honiara; Linda Te Puni, Consul, Noumea; Jonathan Austin, Nuku'alofa; Marion Crawshaw, Port Moresby; Bill Dobbie, Port Vila; John Carter, Rarotonga; Phillip Taula, head of mission, Suva; Martin Welsh, Sydney consul; Mike Walsh, Tarawa.