Classic American and Marine Trailer Adapter (Motive Products - Model 1122)

Features custom cap to fit most early model GM and Ford cars and trucks with internally threaded master cylinder reservoirs from the 1930s through the early 1960s with a 1 5/8" male threaded reservoir cap. Includes deluxe machined aluminum cap and brass swivel fitting.   The 1122 also fits many trailers with a hydraulic master cylinder.  If the master cylinder has a male threaded cap 1 5/8" in diameter at the threads you can use this cap to bleed the brake system on your trailer.