Thanks for the info. This truck was never beat and previous owner babied with mostly in town driving. Oil was always changed when due.
Is is possible the belt slipped a tooth causing the cylinders to fire after TDC causing the knock. The knock started two days before belt snapped and was idling a little rough. I know its possible for a mid mileage engine like this to get a rod knock but I have seen Mazda engines go 300 k and never knock.
Guess I will find out after The belt gets here.
Edit. Just wanted to add that I am pretty sure it is the original belt. Any Idea what company they used from the factory to make the belt?