Greetings from beautiful Costa Rica.
Firstly, where are you located? Your post is a little older so you may have gotten some good information and are sourcing parts. In case that didn't happen read on.......
I have a 2006 Ranger 4 door 4x4 also produced in the Ford General Pacheco plant in Argentina. The 2.9 diesel is indeed a genuine Power Stroke manufactured by International in Brazil. These motors are enlarged displacement copies of the 2.5 liter Land Rover 300 TDI motor. As such many of the parts are interchangeable including the water pump, thermostat, timing belt, accessory fixture for mounting the alternator, most gaskets, fan and clutch and a whole lot more. The motor is no longer made (maybe by the Chinese) but parts can be had most easily coming from England, including a lot of 2.8 specific parts, like alternators. International is now known as MWM outside the US. I am lucky enough to have an MWM distributor here in Costa Rica so factory parts are available. They should have distributors in the US and Canada too since many of their power products have ended up there in various platforms.
One parts source I have also used is LRdirect in the UK. They ship worldwide. you can also aource in the US from Rovers North and a couple of others although they will likely have to inport 300 TDI parts with the exception of filters or other common stock wear items.
Good luck with the hunt.