A driveshaft has an elongated rotary slip sub, a tube sleeve telescopically engaged with the slip sub, a bearing assembly mounted on the slip sub by a roller, a retaining part positioned on the bearing assembly, and a cover extending radially outwardly of the slip sub. The roller is adjacent a movable end of the tube sleeve. A bellows is secured to an adjacent tube sleeve. The retaining part holds the bellows on the bearing assembly. The cover covers the roller.