I have purchased several 2" AL-KO couplers and a hydraulic brake AL-
KO axle from Axle, Inc. The company is easy to deal with. However,
they do not have a mechanical brake option available.
Rex and Noelle always seem to have several AL-KO mechanical brake
axles in stock at Williams. Also just the brakes themselves, which may
be compatible with AL-KO USA axles.
Jim