Like any motor, take care of it, and it'll take care of you.
You have that backwards. The OHV engine was virtually indestructible if taken care of, it just wasn't overly powerful. The three issues I mentioned earlier in this thread plague the SOHC versions in the Explorer too. The first 4.0 I pulled to replace the rear timing chain cassette was in an Explorer.Ah, but there were two different 4.0s used in Rangers. One was not so great, the other, which I believe the Mustang has, is much better. One was an OHV, the other a SOHC.