My chevy s10's radiator blew I replaced it... Drove about 8 miles home. Truck sat overnight. Drove about 10 miles the next day and it wouldn't start back up. The dealership says it's either a blow head gasket or engine. If that's the case why no water or oil drip? how did it drive the 18ish miles after radiator blew?

The head could be cracked also. check the oil if its milky then its the head gasket or head probably. if no then when its running is there alot white smoke that also could be a cracked head or head gasket.the first is antifreeze leeking into the oil system usually cracked head. the second is antifreeze leeeking into the cylinder
so no external leek