Ferguson is widely regarded as one of the best managers in history after winning 13 Premier League titles with Manchester United.
The Scot also won five FA Cup's and two Champions League trophies across a 26-year stint at Old Trafford.
However, his career could have taken an entirely different path had he taken the Rangers job when they approached him to succeed legend Willie Waddell.
But Ferguson has revealed that he made the right decision to move to United instead, where he transformed them into England's biggest club ahead of fierce rivals Liverpool.
"I may have been more attracted to the job had Willie Waddell approached me for it," he told the club's official website.
Premier League clubs ranked by number of permanent managers since 2006/07 Wed, March 29, 2017
Express Sport ranks the current Premier League clubs by the number of permanent managers they have had during the last decade
Play slideshow Getty Images 1 of 21
Which Premier League club has had the most permanent managers since 2006/07?
I felt uneasy about it, so I turned it down
Manchester United legend Sir Alex Ferguson on why he rejected Rangers
"But it wasn’t Willie Waddell, it was John Paton [then Rangers chairman] who spoke to me.
“So I spoke to Scot Symon and he asked if it was Waddell who had made the approach. On finding out it wasn’t, he said he would worry about that as Willie was still running the show.
“That was one of the reasons I felt uneasy about it, so I turned it down.
“I think I did the right thing going to England from Aberdeen.”
Get Quotes on Home Insurance
Ferguson left United four years ago, with his old club going through three managers in that time.
David Moyes and Louis van Gaal both paid the price for failure, while Jose Mourinho looks to have steadied the ship after winning three trophies in his first season in charge.
Sir Alex Ferguson has revealed he was offered the Rangers job in the 1980s
Sir Alex Ferguson went on to win 13 Premier League titles with Manchester United
And, speaking last week, the 75-year-old gave Mourinho his full support and insisted the former Chelsea manager was the right man for the job.
"He's a very talented manager, no question," he told Sky Sports.
"I think United have done really well. I think with the draws, they've played really well in a lot of those draws.
"If even six of those draws turned to wins, that's 12 points, and they'd have been up there.
"Hopefully we can start winning things, because I'm sure that's what (Jose) wants.
"We do still chat, as I did with Louis van Gaal and with David Moyes. United directors in my time were always very supportive of me, and I hope that continues for them."