I'd like to expand a bit on this rear spring cushion replacement issue.
While all mean well, I think some take the safety issue here just a bit lightly. While replacemet of the cushions is a DIY job if you've got the right tools and care, it can be dangerous.
They key task is relieving spring tension on the cushions so you can get the bolt out. The generally-accepted technique is to support the rear of the car on jack stands, pull the rear wheels, then use a floor jack or a hydraulic bottle jack to raise and hold-up the end of the leaf spring while you pull out the bolt.
A problem sometimes comes with the main leaf being at an angle and not flat to the jack pad causing the jack to slip sideways as you lift. Once you place the jack and begin to jack it up, you want to watch very carefully for any jack slippage. The higher you move the jack, the more spring tension you have. If the jack slips and pops out, either don't be in the way or have good health insurance.
Once everything is safe and the spring is up, remove the cotter pin and nut, withdraw the spring bolt and change the cushions. My personal choice for those cushions are polyurethane such as what Vette Brakes sells but OE rubber is ok.
On cars with rear stabilzer bars, you might need to move some of the bar hardware out of the way.