w/ no shocks on the rig, find an obstacle to 'flex' it out on, and then measure full extension; mount center to mount center, and then compress w/ a similar obstacle to get collapsed length...all 4 corners.
I bought 4 procomp es3000 for $130 shipped' 4wheelparts; found thier app chart online.
you can find an application chart for whatever brand shock and select correct travel and mounts
hth