Jim, What direction are you going to go with your YJ spring install? The RR kit has some issues but is a pretty easy way to go and will get you the ride/comfort/ flex your after.... relatively easy. If you choose to DIY it you can get everything literally perfect..... but that takes more time, space, tools. Now is not the time to be cutting the spring perches off of your D30...... That is the very last thing that should be done to complete your suspension upgrade. You won't know what your caster needs to be adjusted to until your suspension is set up. If you get it all set up and later decide to change your shackle length..... you will need to re adjust your caster. That's the time for caster shims...... I went through all this just last winter. Starts on page 16 of my build thread. Norcal69's Common Sense Build. I am in no way saying that this is the only way to do it.... but my jeep can be driven 70mph on the freeway, no hands on the wheel.