Or search: tune, tare, fitting, voicing, discount, adaption, laxation, alignment, allowance, deduction, loosening, adaptation, alteration, betterment, tightening
2 Syllables: SU
buxom, Buxton, cousin, Covent, custom, dozen, duction, Dutchman, husband, judgement, judgment, Justin, Muslim, muslin, oven, Prussian, Putnam, Putnam's, roughened, ruffian, Russian, suction, Tuscan, Upton
3 Syllables: USU
abduction, accustom, adjustment, Augustan, combustion, concussion, conduction, construction, corruption, deduction, destruction, discussion, disruption, eruption, escutcheon, Etruscan, induction, instruction, irruption, obstruction, percussion, production, readjustment, reduction, reluctance, reluctant, seduction
4 Syllables: UUSU
interruption, introduction, reconstruction, repercussions, reproduction, unaccustomed

Found 57 words across 3 groupings. Skipped 27 excess words of a similar stem.