I don't mean to teach you to suck eggs Charis but you really need to diagnose and find the fault before just buying parts and fitting them. That way lies financial ruin.
Can you record the sound somehow? Perhaps get someone to walk/ride alongside to try and pinpoint the noise. When exactly does it occur? Over bumps, accelerating hard? On the overrun? Has it always been there,come on slowly or come on suddenly? Do you get a heavy ticking noise from the front when turning? Have you jacked the front up and looked underneath at the prop shafts and rotated them back and forth? Try moving every bit of the driveline. Try isolating each bit by holding something and turning another part. Look for any backlash (a bit that moves a lot more than normal while what it drives stays still). When you changed the drive flange, what did the splines look like? Were they reduced/grooved,was the flange a sloppy fit? Have you checked your UJs and prop shaft spline? There's a whole lot of expensive bits between gearbox and wheels.
