If the original owner didn't keep up with the oil changes, at 123K miles, the damage has probably already been done. Mopar originally expected a 150K life span on the 4.7.

That said, I've heard of some them going well over 200,000, but probably a lot more haven't made it to the 150K.

The 4.7 is unreliable and under powered in a heavy truck like that Aspen, but You may be lucky. Gene