yeah im not so sure about those instructions to set one control arm longer than the other. The stock control arms are the same length yes? Jeeps come from the factory with more caster on the drivers side than passenger to compensate for different shaft lengths and road crown yes? So if this is the case the difference in caster must be built into the frame or axle side bracket placement or the axle c's which means there is no need to set one control arm longer than the other. Just like stock control arms are the same length your adjsutable arms should be set to the same length. I have never had a problem doing it this way as a matter of fact last alignment I had showed caster higher on the drivers side by .3 degrees and my control arms were each set to 23" exactly. Just my 2 cents here
I can't pull them up to post for you right now, but if you look at the factory alignment specs they call for .2 degree more on passenger than driver. Prefered settings are 4.2 degrees driver, 4.4 degrees passenger. You are correct, the stock arms are same length both sides, so the factory variance is either in the axle or frame side brackets. (My bet is it's in the axle side.) I've run a Teraflex suspension on my '09 since it had 700 miles on it (now 51,000), starting with their short arms & stock front housing, now with long arms and Teraflex's R44 housing. I've always followed their suggestion and have the passenger side arms set about 1/8" longer than driver. Tracks straight as an arrow, no drift issues and no odd tire wear. Bear in mind I also run manual front hubs, which eliminate the torque unload tendency of the long passenger side front axle shaft. Roads here in SW Colorado are crowned to ensure runoff, in areas where there's lesss crown I'm not sure the staggering would be necessary or adviseable beyond what Jeep recommends.
'09 JKRU. 4" Teraflex long arm, Teraflex R44 housing, Teraflex / Fox Resis, Poly Performance skids, Nemesis Billy Rockers, Nemesis flares, 37" ATZ P3s on 17" 5x5.5" Trailready HDs, Spyntec hubs, Teraflex BBK, Mopar BBK master/booster, Superior front & Alloy USA rear axle shafts, CTMs, Reids, Synergy drag link & tie rod, WTOR hydro-boosted steering, 5.38s, TF Dual Rate front bar, TF bumpers, Warn Powerplant, Tom Woods shafts, AA xfer case cable, Kilby canister relo, RH4x4 cage.