I assume Dodge is using the same factories to build the new trucks as were in use when my 01. 5 was built. I am working from memory here, so forgive me if I make a mistake. If I remember correctly, there are THREE places than make the Dodge trucks. Besides St Louis and Saltillo, I think there is a place in Canada. I know there is a letter in the serial number than tells where the truck was built. Both of mine were built in Saltillo.
The quality of the Mexican built trucks seems to be excellent. I have no personal experience with the other plants, but I would expect they too are good. Only negative I see with a Mexican built truck is that it would be rather difficult to read the line sheet unless you can read Spanish! Mine are both in Spanish... which is no problem for me.
Steve