I believe this will be the first Super Bowl between one coach who replaced the other. Carroll was the Pats coach before Bellichick.
Actually, no, that would be the second, Shula replaced Weeb Ewbank in Baltimore and they faced each other in SB III.
How about 1999 when Shanahan faced Reeves in SB XXXIII?
Close.
OAK-TAM in 2003. Callahan vs. Gruden, after Gruden was traded to TAM.