Hi Mason, I am pleased to assist you. The specific thread size for this brake line is not readily available in the provided sources. However, brake lines typically feature threads that are 3/8"-24 in size. The 3/16" brake line is a common size used for brake lines in many vehicles, particularly for the connection points in the braking system. It's advisable to double-check compatibility. If your vehicle information matches this product, use the link below to order while the part is in stock. Your order will come with a 30-day post-purchase price match guarantee. I hope this helps, and enjoy shopping! https://www.carparts.com/brake-line/motorcraft/mibrtr67?can=CPGG4850_CSQA_20241226

Hi Alan, I'm pleased to assist you. No, this does not fit the 2000 Lincoln Navigator Base 8 Cyl 5.4L. We have available the direct-fit rear passenger brake line compatible with the vehicle. However, there are 2 sizes available. Click the link below to choose among the options we have available. Place your order at a reduced cost while supplies last. I hope this is helpful. Enjoy your CP shopping experience! https://www.carparts.com/search?q=Brake_Line&itemsperpage=15&refinements[location]=Rear-comma-_Passenger_Side&vehicle[cylinders]=8&vehicle[liter]=5%2E4&vehicle[submodel]=Base&vehicle[model]=Navigator&vehicle[make]=Lincoln&vehicle[year]=2000&can=CPGG4850_CSQA_20230809