Read this, as Commanders are The WH twin.
I have the Navigator & the only benefit over a standard Grand is the factory bash plates. The GPS is not updatable & will leave you with 3 holes on the dash when removed.
As in the Commander post you should listen for a thud/knock when driving, this generally means front diff bush's &/or sway bar bush's need replacing.
Factory springs sag over time so you will get more height then advertised if you install a lift.
If you can, remove the engine cover (2x10mm bolts) & inspect where the turbo hose connects to the turbo. The seal at the turbo should be black in colour not orange, if orange the intake tube will need replacing as the orange seal ones allow oil to leak onto the swirl motor which will eventually kill it.
One other thing that’s not easy to check but highly recommended is to check the transfer case fluid, if its red in colour walk away (should be yellow/clear) or factor in the $2000 replacement cost into the price. Red ATF destroys the T/C over time & shouldn’t be used.
Other than that it’s a used car & just give it a though inspection.