I fitted AVOs as my rear shocks were knackered. They work a treat and even
noticed the improvement. But...that was to cure a known problem of the shocks. I agree re you may have poor leafsprings, too soft. The suggestion to check any impacts on a tooltray above the axle is good too. There were witness marks on mine to show contact so padding, securing jack etc have cured this. The wooden panel on the shelf was also "tightened down" with rubber and foam too.
In fact, anything that moved and might cause rattles/bumps was secured where sensible using neoprene,rubber tape,cable ties.
The front chassiis does still ground on speed bumps if taken at the wrong speed but only rarely now as I am more careful! Beware tailgaters though...they seem to underestimate how long I take on bumps due to lower speed!
