injectors

Hello, Been looking at a lot of video's from fourby4diesel on youtube about the D4D's in prado's and I was wondering did some of you change the injectors and/or the injector seats and at what point? Tried to look up through the oil plug on the sump, to see in what kind of state my oil pickup...

I have a kzj95 prado and I’m interested in doing the injectors. It has 126k miles. Should I replace the injectors or rebuild? I’m mechanically inclined so the scope of work doesn’t worry me. Either way, where can I find the parts for rebuild or the new replacements? A google search hasn’t really...