While they sold those trucks in the US, I seriously doubt they sold the diesel versions of them. (Diesel is not at all common in the US except for larger trucks, and that is a compact pickup.)

However, maybe in Mexico? Jon, can you call a Mexican Mazda dealer's parts department? Maybe he can help. He should also be able to verify that the engine you have is an R2. Assuming that it didn't get a nasty scratch right across the serial number when it fell off the back of the truck.

Looks like there are dealerships in Mérida (which seems to have two locations), Villahermosa, and Guatemala City.