There is a "Trusted" source out their ..... there is a company in Houston called " Engine World USA " who specializes and pledges to sell only and only rigorously tested engines & transmissions. Their website url is www.UsedJapanMotors.com. They have been in business for over 8 years but since their are very few reliable sources for tested Engines / Transmissions because one can't trust a Junk Yard.
They seem to have a very successful business model. They bring 90% of their Japanese Engines & Transmissions from Japan. We all know due to strict transportation laws Japan is the only country where considerably low mileage Engines & Transmissions can be found. They have their own network established in Japan for over 15 years.
So according to the research and all data available, Engine World USA is the best source for Low mileage Japanese engines & Japanese Transmissions.
They specialize in Japanese brands like ACURA, HONDA, TOYOTA, NISSAN, MAZDA, MITSUBISHI, LEXUS, INFINITI, SUBARU, SUZUKI & ISUZU.