Gordon has a bit... the chorus "show, show, show, show me" part is him in VALIS... he sings the quieter chorus lines in The Truth, ".... You complete me". Obviously the chorus "ooos" on Octopus, and live he sings the "No" parts before YESSSSSSSSS in 3x3.
There's probably harmonizing but these are the parts where you can actually hear him 100%
And of course MATT provides the screams in We're Not Good People, and the god-awful Coliseum (lol, hate that track)
Ah, makes total sense! I'm hearing him more now you've mentioned that, it's a far cry from 'The Marshals Are Dead' but hey ho!
Coliseum is my least favourite, but I don't dislike it... But I do think Mean or Lean should've replaced it.