We often get questions about parts support for certain JDM or other vehicles that we sell here in the USA. Even though the vehicles may not have been sold here originally, often they share parts with other vehicles. We normally call this kind of thing PARTS BIN SHARING. Many of the same suppliers provide parts for many different models, and those parts are shared amongst cars. Like keeping any 25, 30, or 40 year old car working, and maintained, it requires a little more work than a brand new car from the dealer. However it is not impossible, and many times not really even that difficult.
Most car types have a nice support network of owners that are willing to share information about what works, what doesn't, cool and unique modifications they have done. You can find them in Facebook groups these days, but in the past it was automotive forums. Even if the support network doesn't exist, it just requires a little bit of work and the internet. Normally in the country of origin, there are support networks and information. With the power of Google translate, you can learn a lot of information.
As far as shipping or obtaining parts from overseas, we have had times when it took less time to get a part from overseas, than to get it in the US. If the part is in stock overeas, EMS can often get it to your door in 3 days. Parts coming across the US often take a week or more. This of course means that for some things, you need to plan a little more far in advance, but it is how it is with nearly all cars. Even brand new cars wait on parts.
The easiest place to find most parts, if you are in the US is eBay. For instance a search like TOYOTA CHASER, BRINGS UP 3610 RESULTS.
There are thousands, and thousands of parts listed on eBay. Some in the US, some overseas. Like any source, some people love eBay, some people hate it. We find it a good resource to find parts.
Next there are a lot of online parts sources and suppliers out there in the world. We have used the few below, and found them to be good resources to have. They have parts for Toyota, Nissan, Mitsubishi, and Honda. Just enter the chassis number, and you can search out the parts you need. Even if the parts are discontinued, at least you have a part number, that you can use to search other sources. Many places have what is called NOS parts, or New, Old Stock. As in parts that were never sold, but might be 25, or 30 years old. Just sitting in their warehouse or storage. EPC-DATA.COM
The Holden ute, actually uses a Nissan air filter. Just one example of parts bin sharing, even amongst different manufactuers.