So much to check, what's the car? Wheres the tracking? Tyre pressures around 16 psi only? They should be. Check your camber. The nuts that keep it constant can become loose. Is it a dedion? live axle? Either way the bushes at the rear of the car can get shot over time. As to springs, you'll also need to consider your ARB before deciding on a new spec. How about looking for play in the steering column? The join in the column can work lose. The rack can wear also, some are adjustable. When did you last check your wheel bearings (front) for play? de dion - Where are your dedion tube trailing arms fitted, they;re best in the lower position. Give ewverything you can wiggle on the car a good wiggle and get a friend to help that's before you start replacing bits.