I think all of these factors make a difference on shock/Suspension lenth. Please don't get board with the extra information.
I have a 98 4 door on 35" MTR's with a full interior cage running Rock Crawler 8" Coils, Aco's adjusted for 1 inch of lift and Long Arms in the front, I have a fairly light front Bumper with a warn 9000 winch. I'm currently running the 12" 5150s
The up travel seems to be fine but i'm limited on down travel. I will be trying the 14" 5150's soon.
Side note the coils are really soft and for my application i would like more spring rate on the torque coil. I'm still not sure if i like the 5150's yet? They seem to work well, but to soon to comment either way. I took off Rancho 9000's which worked good, but wanted to try the 5150's.
In the Rear i,ve got 8" Alcans, with a inch shackle lift. My shock mounts in the rear have been moved up to be even with the 8.25 housing
I'm running the 12" 5150's
In the rear they are to long for the shock mounts being moved up, but would be near perfect for the stock mounts, and a lighter XJ
I'm running alot of weight in the rear, Huge Toolbox, full of tools, 2 Drive shafts, both front axels shafts, rear shaft CO2 and so on
My jeep will be going on a diet soon. as should i.
My rear Bumper is a heavily supported rear stinger which might be equivilent to a normal rear tire carrier bumper weight. I'm also running about 60# of rear qtr body armor,
Next step for me is to relocated a rear shock cross member. Possibly tied into the interior cage, Any ideas guys
Hope this helps
Cruzzin_XJ