Truck using lot oil. No leaks not burning,no smoke
What is your definition of (a) “lot (of) oil”?
One quart per 500 miles?
And the usual:
Miles on odometer?
You say it’s using oil, but “no leaks, no burning”. If it’s not leaking oil, it’s burning it. Burning oil was a pretty common problem for the GM trucks equipped with “active fuel management” of that era (5.3 liter).