Vowel Shortening: [+syll] -> [-long] / __C{C,#}
... or, better, given that Yokuts syllables are CVC at their most complex...
Vowel Shortening: [+syll] -> [-long] / __[Coda C]
If the UR for aorist passive is /-it/...
Vowel Deletion A: [+syll,-long] -> Ø / VC__CV
Vowel Deletion B: [+syll,-long] -> Ø / V__
or, less elegantly, [+syll,-long] -> Ø / V{C__CV , __}
... or you could choose to use ...
If the UR for aorist passive is /-t/...
Epenthesis: Ø -> [+syll, +high, +front] / C__C{C,#}
... or, better, again assuming a CVC syllable structure...
Epenthesis: Ø -> [+syll, +high, +front] / __[unsyllabified C]
Deletion works, but epenthesis is more elegant when involving syllables!
Vowel Harmony: [+syll, αhigh] -> [+round] / [+syll, αhigh, +round]C0__
Vowel Lowering: [+long] -> [-high]
Aorist: /-hn/
Aorist Passive: /-t/
Comitative: /-mx/
Mediopassive: /-n/