Good point...I meant to mention that.  There is 25,000 pounds pre-load on the spring so you can imagine what it would do if it got loose.

If you end up needing to compress the spring slightly be sure to place steel blocks in between spring and the stops.  Don't depend on the nut at the rear of the spring to hold it alone.  Spin up the nut at the rear of the spring too once you have the spring blocked back.  

If your spring looks bent or isn't laying in position straight or isn't against the stops straight you may want to have someone with experience take a look at it....don't take risks!

The threads on the bolt in the center of the spring are very often in poor condition and aren't safe for containing the spring.  A lot of guys won't remove a spring using the old bolt.  They pull the track adjuster like you're doing and then install a new bolt and nut to contain the spring during removal.....or....just torch the spring.