Tom Brady was VERY close to making that huge change -- with the QB considering swapping his number after joining the Tampa Bay Buccaneers.

So why #7?? 'Cause Brady's going after that 7th ring, baby!!!

Bucs GM Jason Licht made the major revelation in an interview on the Peter King Podcast this week ... saying Brady was totally fine with letting star receiver Chris Godwin keep #12 'cause he had a new number in mind.

Licht breaks down the convo after the move to TB was a done deal ... and it's the most Brady story ever.

"After we had talked and we knew that this was gonna happen, I said, 'Hey, there's one other thing. It's a small thing but maybe a big thing," Licht says."

"We have a #12 on our team and he's pretty good, Chris Godwin. What are you thinking about that?'

Brady's response?? ... "'Oh, he's a great player, I'm not going to take his number. Know what number I'm thinking of? I'm thinking of taking maybe #7. Is that available?'"

"I said, 'Yeah, I think it is, why #7?' He goes, 'Going after that 7th Super Bowl.'"

It's crazy to hear Brady was prepared to ditch #12 so easily ... after all, the dude has an entire TB12 brand tied to his beloved digits.

Of course, Godwin ended up switching to #14 to let Brady take #12 ... and TB12 is one win away from that 7th ring.