It sounds like you need a new axle. We bought one and brought it to a garage, the mechanic who is very trust able told us it was not the axle. It is the transmission slapping or something like that. I asked my brother who also works on cars and he said it sounds like something is binding. When you shift gears (from park to drive, or drive to reverse, or whatever) it makes a click, click, click noise. I don't know how much longer it will last, and either do they.

The mechanic said he has seen it before in the caravans, and it could go in a month or last a while. But obviously it isn't just mine!!