One of my favourite bands and songs. Back then they didn't have DAW's or programs to do harmonies, everything was done on tape by real people.
You can simply duplicate this by singing an octave below and adding harmonies if you want. That's all this is. Check out Melodyne if you want a great program to do harmonies for you.

Thanks for the tips! I am definitely going to sing parts like this myself, no autotune cheating for me!

ThirdBird, post: 379560 wrote: Thanks for the tips! I am definitely going to sing parts like this myself, no autotune cheating for me!

While you are at it, learn to sing really evenly so you don't need a compressor, tame your sibilants so you don't need a deesser, and really work on your tone so you don't need an eq. I'm being snide of course. But unless you are recording direct to two-track you are "cheating." Miller used every recording trick available at the time. Of course, if your goal is to become a better singer, then by all means work on your pitch. But you are trying to make a recording, and you have already accepted all the "cheats" of multitracking, effects, etc. Pitch correction isn't really any different.