A diesel engine can be hard to find in the U.S. because not many cars are made with one just yet. These kinds of vehicles are becoming more popular by the day though, so you may be in need of a replacement engine for your car. If this is the case, consider buying from some of the sources below.
You can call up a diesel car manufacturer that may make parts to fit your vehicle. If you have a stock diesel engine, you should be able to call the manufacturer up and get a replacement one of the exact same model. If the manufacturer does not make the engines directly, they may be able to tell you where to get one.
Sometimes the service department of a diesel car dealership will have access to the replacement engine you need. Though this may not be the case if you are looking for specifications beyond what comes stock for your car. These dealerships may be in direct contact with vendors who can help you out, so do not lose hope.
There are sites online that offer diesel engines for sale, both new and used. You can look for the exact one you have in your car or consider upgrading to a larger one if it will fit. If you do manage to find something online that you like, at least do a few comparisons to see you are getting a good deal. You can save a lot of money with some simple research.