My gearbox is making a whizzing kind of noise and is very clunky, i have nailed the noise down to the gearbox by taking a prop off and took it out of difflock so i could leave it in gear and get underneath to pinpoint it. would i need a new gearbox or could it be something else? I've just taken the engine out to replace the clutch and release bearing because i thought it may have been that but it wasn't.

where would be the best pace to get another one as i don't want another gearbox with high milage but don't have the budget for an recon ashcroft type box.

any help appreciated as i just want to get it back on the road