Neng, the Armada and Titan _front_ suspensions are identical for model year '07. The rear is completely different. If you don't get an answer here, try the TitanTalk.com forum. It is the most popular site for Titans and I doubt that you can stump them. ClubTitan.org is another option. It has great history but isn't very active any more.I recently purchased a 2007 Armada SE to be used for towing a 4000 lbs camper.
It had 50K miles on it and the right was bumpy.
While towing, I experienced bump steer. I had not experienced prior to that.
From reading the forums,I replaced front and rear with:
Bilstein 24-197656 4600
Rancho RS5396 RS5000 Series Shock
The ride got smoother but at the same time, it got scary.
the car bounces on the slightest bumps and bumps steers on very small bumps.
I removed the Rancho shocks and put the stock back on the rear and the bump steers went away.
I hope the Rancho was the right one and I just need a 4 wheel alignment.
Bump steer on the Titan is almost unheard of. Especially on an IFS. I can't recall any recent threads on TitanTalk where bump steer came up. I would try getting it aligned. I've heard of that resolving bump steer on a SFA (Solid Front Axle). I would also check for other worn/broken components. My Titan at 99K miles drove very smoothly but I did have some aftermarket components on there (UCA and coilovers). At 50K miles your Armada should be easy to drive unless it was abused.
On the Titan forums the OEM and aftermarket Rancho shocks are universally reviled. On the Ford truck forums (mostly the Superduty side) the aftermarket Rancho shocks are thought well of while the OEM Ranch shocks are considered crap.
I put Rancho 9000XL shocks on my F-350 and it made for a nice upgrade. Bilsteins are generally considered to be the best bang for the buck on the Titan. I would have gone Bilstein on my F-350 but they failed to come out with shocks that fit the 2017 in time.