A friend has Frontier with this engine and a mechanic told her the timing belt broke ( 160,000 miles). He just said it would be expensive to fix. To try to get a more detailed idea of how expensive , I am wondering if her 2003 Nissan V-6 ,3 L , ( USA) is an interference type engine .
The engine in your friend's Frontier should either be a VG33E or VG33ER (supercharged version). These displace 3.3L and they are most definitely interference engines. If the belt broke, your friend is most likely looking at a lunched engine. It will most likely be expensive, not only to replace the engine, but the labor involved in it as well. The VG33E engine is built here in the US, so I doubt you're going to find a JDM equivalent (but I could be wrong).