Arnold asked Postecoglou and his fellow former Australia head coach Guus Hiddink to speak to his players before Friday's game at Wembley.
"The speeches by Ange were very similar to what we've been saying for years," said Arnold.
"Doing it for the kids in Australia, the nation and the supporters."
Australian Postecoglou was appointed Tottenham manager this summer and has guided Spurs to the top of the Premier League table after eight matches.
Australia are underdogs on Friday having beaten England only once in seven meetings, a 3-1 victory at Upton Park in 2003.
Their most recent meeting saw them lose 2-1 at the Stadium of Light in Sunderland in 2016.
They are 23 spots below their fourth-placed hosts in the Fifa world rankings.
"I know one thing - they will run until they drop. The energy will be there and they'll put in the performance of their lives," Arnold added.
England manager Gareth Southgate said the match with Australia renews "one of the great sporting rivalries" and England "will be in trouble" if they do not take the Socceroos seriously.
England are playing only their second friendly since March 2022.
Arsenal striker Eddie Nketiah and Chelsea defender Levi Colwill could make their England debuts.
The Euro 2020 runners-up will also be looking ahead to next week, when they can seal their place at next summer's championship in Germany.
Southgate's team have a six-point lead in Group C over Italy, Ukraine and North Macedonia, and their match with holders Italy on Tuesday could decide top spot.
"Our mindset has got to be spot on. Equally, we've still got a bit of work to do to qualify for a European Championship.
"We have good players and we need to give people opportunities to show what they can do."Jack Grealish has two goals in 32 caps for England
England midfielder Jack Grealish hopes he can add a trophy with his national side to his already illustrious CV.
Last season Grealish won the Premier League, FA Cup and Champions League with Manchester City.
"I don't mean this to sound weird but it is difficult in a way because you have such a high of winning the treble and then you do think 'what would ever top that?'" he said.
"Obviously doing something at international level definitely would."
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