Rust inside rear wheel wells, Rust under tailgate. Rear Tailgate window should go Up and Down with Switch in Tailgate and Dash Switch. Tailgate should open easy when window is down, Should go back up when gate closes.
Lock in hubs pull back on transfer case lever and make sure 4 wheel drive works. Make sure that it goes back into 2wd and stays there the NP208 shifter inside wears out and will not stay in 2 wheel. If top has been off check for leaking.
The rest is not specific to Broncos.