Your Time Is Gonna Come" is the one.

Yes, it’s “Your Time Is Gonna Come” from Led Zeppelin I. John Paul Jones handles the lead vocal, with Robert Plant adding harmonies — an unusual reversal. It’s the only Led Zeppelin song where Jones sings lead from start to finish. (He also sings lead on “Black Country Woman” live occasionally, but that’s a rarity for rarity’s sake. The studio version is the definitive answer.)

Plant once joked that Jonesey sang it because he was the only one who could get the key right. True or not, it’s a great example of how underutilized Jones’s voice was. He’s a solid singer — just didn’t want the spotlight.