The Catholic Message Board

As far as I remember, the words are the same, but the music is different than what I learned back in the early 60's.

Old songs are often set to a different tune

I'm not sure what tune you heard. This is the only one I know. https://www.youtube.com/watch?v=w8bvfvdjZzI

That's also the one on the OCP ( ) website.

I did find a web reference to a different setting in The People's Mass Book, but I don't see that used much of anywhere these days. Perhaps you found a holdout.

I wish I could read music so I would know if the reason we had three hymns set to the exact same tune is because they all had the same tune in the hymnal or because the organist only knows that one tune and just used it for everything.

The hymnal usually gives the name of the hymn tune somewhere.

Are you sure they all are the same tune? The timing can make them sound similar. This is the only version of 'O Sacrament Most Holy' that I've ever known since the 60's (in Australia). It's not a terribly professional version.

https://www.youtube.com/watch?v=HazUnCaKMps&t=25s

'Holy God we Praise Thy Name' has a very similar timing and notes and does sound similar.