What now! strange sensation..

Could someone please suggest where I should start looking with a rather strange problem that has just started occuring.

When going down a reasonably flat straight road the Disco starts to shift from side to side, the best way I can describe it is that it feels like a large heavy weight is swinging below the car like a big pendulum.

The feeling comes through the drivers seat not the steering and although hard to say exactly it feels like its coming from the centre of the car/gearbox area.

When driving it's like having your bottom pushed gently from side to side, something which in all honesty I'm not into, so I'm keen to get it fixed.

Check the A-frame ball joint, UJs on the prop and the panhard rod bushes - then again it could be none of those ...

there will more folk along shortly

thats where id start, all trailing arms bushes a frame, any noise or just sway, any particular speed does it start stop?

Don't forget the bushes on the A frame where it attaches to the chassis