I was driving my wife's 2004 Disco tonight on the highway.
When I pressed the gas pedal and then again when the pedal is released at speed there was a noticeable clunk.
Nothing at start from a stop, just while moving.

Thanks in advance everyone.

 

It's just a Rover thing.

 

When i let off the gas on my disco i get a slight clunk and slow down. Almost feels like some kind of slack in the drivetrain

 

Same thing happens in my 01 discovery. Most the time it happens when I'm braking for a red light then it turns green before I come to a full stop and I get back on the gas again. When I hit the gas again is when I'm getting that noise. Please update us if you find the source of the noise.

 

It's probably just drivetrain slack, as previously mentioned. But it could also be worn U-joints, which I've read is especially troublesome on a D2's front driveshaft. (Or propshaft, if you prefer the British term.) Crawl under it while it's in park, preferably while cold so you don't accidentally touch an exhaust pipe. Grab each driveshaft and try to move it. If it twists a little bit, it's just normal drivetrain slack. If you can move it side to side or up & down at all, you need new U-joints.

Here's what one of mine looked like:
I must be doing something wrong, no idea why the pic looks like that.

 

Happens on mine as well even after a couple new prop shafts.

 

It is normal based on our t/case design and can not be fixed, nothing is wrong it is just a Rover thing that does not mean you have a problem.

 

My '01 does it too. I replaced the front propshaft and rear rotoflex, still does it.
Im not worried about it.

 

If you really slowly push the gas pedal it doesn't clunk almost at all.

 

My 03 does it as well, not as bad after a new and beefer drive shaft.