The UM coach was talking Super Bowl on his podcast, "Attack Each Day: The Harbaughs' Podcast," when he revealed TB12 is so great ... he needs a sculpture on campus.

In fact ... Jim says Tom has proved so much in his 19-year NFL career -- the university should now be OBLIGATED to immortalize him!!!

"Tom Brady -- greatest of all time -- and he's lapped the field in football. He's lapped the field."

"You're synonymous now with Babe Ruth, with Michael Jordan. The university that he attended should build a statue."

The only question left for Jim? Where to put it.

Harbaugh, his dad Jack and UM Director of Recruiting Matt Dudek had the debate ... and seems they're settling on somewhere near Michigan Stadium.

It's interesting ... 'cause when Tom was at Michigan -- a whole lotta fans thought Drew Henson shoulda been the starter during Brady's time as signal-caller.

But hey, nobody remembers that now, right?!?!