Currently sitting at 428,000km 266,000miles and wondering when I should be expecting this engine to go. Still runs strong and only issues are erratic fuel gauge and heater only has defrost setting as the flap in the dash doesn’t move into the other positions.

 

Too many variables combined with too little information to even venture a guess.

 

Good looking truck. Fix the items you know are in need & the known notorious failure items for your model.
Cut all service routine intervals in half, drive it like a ChurchLady on Sunday, & it may go another 200k.
Or she may still blow up & die backing out of the driveway tomorrow; that can also happen to brand new vehicles.
Recommend taking good care of your vehicles no matter the age\mileage,
then hope for the best & be prepared (financially & mentally) for the worst.