Something I had previously posted that may be of help:

I used factors of 40% for compression and 60% for extension, meaning that I anticipated that the shock would not compress or extend more than those factors for my usage. I use the truck on our property, trailering, etc, no extreme off-road with lots of high angles, etc.
I used Pro-Comp ES3000 shocks with boots, they seemed to work fine for my use, but of course everyone has their picks on shocks. Not interested in debating that, just giving an example of how I picked shocks.

If you look at the Pro-Comp site, they list specs for their shocks. I happened to have had a chart on this, easier than sifting thru many web pages. But the info is there.

As an example:
At ride height, the distance between top/bottom mounts on my truck was 24" on one set of the front shocks (have quad shocks on the front).

Looking at the specs, after some trial and error and looking at several shocks to get me generally in the 24" installed height range, there was a ES332010 shock that shows 31.76" extended, 18.25" compressed:

• <LI itxtNodeId="1011" itxtHarvested="0">this shock has 13.51" of travel. <LI itxtNodeId="1010" itxtHarvested="0">40% of 13.51" = 5.4" for compression travel <LI itxtNodeId="1009" itxtHarvested="0">60% of 13.51" = 8.1" for extension travel <LI itxtNodeId="1008" itxtHarvested="0">24" ride height plus 8.1" = 32" extended
  
• 24" ride height minus 5.4" = 18.6" compressed.
  

My numbers of 32" and 18.6" were very close to the published 31.76" and 18.25" numbers so I went with the ES332010 shock. I went thru the same selection steps for the other set of front shocks and the rear shocks as well since these other sets had different mount spacing dimensions. That was in 2003 and I never ever had any issues with bottoming out or overextending.

This time around, when the truck is reassembled I will go thru the same process, especially since I'm changing the location of the rear axle shock mounts and also adding 2 more shocks in the back as well. If you are anticipating significant off-roading you can increase the compression and extension factors and the opposite is true as well. If its street driven, then the factors can be reduced.

Hope this helps. This may seem like a lot of work but it's important to stay within the normal operating range/travel of the shock to avoid shock or mount damage. Maybe someone has a different and better way, this is what I did and it worked fine for me. <!-- / message -->


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