rbrodeo

hey i own a 89 rodeo ute with a rb20 det motor with a vipec computer twin plate clutch an couple other goodies recently 3rd gear became really crunchy now its at the point were the box is driving with a ticking noise an a vibration, i can tell its on the way out just wondering if this is a comman problem an if i should or could fit a rb25 box behind the rb20