Hello all, hope things are good

..my latest '82 SJ gets a wobbly frond end when going over a bump..seems to be on the left, but is really inconsistent (not every time) in a 5km drive today it did it 4-5 times..doesn't do it on the flat and most of the time I consider the steering to be fairly sweet under normal conditions! makes the steering wheel wobble too, which is proper disconcerting!!
Any ideas greatly appreciated..
Andy