Oil pressure 2008 Silverado

Engine light comes on low oil pressure. Dealer wants to
replace engine. They said there is 50psi at the Oil filter, but
Very little pressure at the top of the engine, in which the
sensor says low oil pressure. Sensor has been replaced
about a week ago. There is no knocking or weird noises.
No smoking. Truck has 209,000 miles on it. They say to
actually find he problem is about 20 hours of labor. They
refer to it as a clogged artery. Engine oil isn’t reaching the
bearings. Any less expensive ideas to fix this problem
would be greatly appreciated. I haven’t changed the oil,
but you would think the dealer would try that? It’s due in
about 2,000 miles. There is no metal shards in oil.