Buck, luck, pluck, suck, struck, tuck, truck, duck.
UCT.
Conduct, deduct, instruct, obstruct, aqueduct. The preterites and participles of verbs in UCK.
UD.
Bud, scud, stud, mud, cud, blood, flood. ["Suds" rhymes plurals of nouns and third person present singular of verbs in UD.]
UDE.
Rude, crude, prude, allude, conclude, delude, elude, exclude, exude, snood,† include, intrude, obtrude, seclude, altitude, fortitude, gratitude, interlude, latitude, longitude, magnitude, multitude, solicitude, solitude, vicissitude, aptitude, habitude, ingratitude, inaptitude, lassitude, plenitude, promptitude, servitude, similitude, lewd, feud, brood, etc., and the preterities and participles of verbs in EW, UE, etc.
UDGE.
Judge, drudge, grudge, trudge, adjudge, prejudge, fudge,§ smudge, nudge, budge,§ sludge.*
UE.