Welcome to TRS
Rangers hold up pretty well, 108k miles is barely broke in
But like any used vehicle its a roll of the dice
2005 was a good year, no PATS(passive anti-theft system), so it doesn't need "transponder keys"
The 4.0l SOHC engine should have the good timing chain tensioners
If an automatic trans that's the only downside, for ANY vehicle, it will be a 5R55E model transmission which is a good one as far as automatics go, just service it and if it doesn't have a 2nd trans cooler add it, best $60 you can spend on any automatic
The 4x4CM(control module) is behind the radio, if 4WD system quits that's the weak point in 2001-2011 Ranger 4x4s
If 4WD quits and 4WD lights don't flash then its the 4x4CM, if they flash then its the shift motor on transfer case
Best way to keep 4x4 system working is to shift into 4Low then back to 2WD once a month, just sitting in the driveway
Biggest killer of electric shift 4x4s is disuse, they sit for 11 months and then people are surprised they don't work