Dale Walker provides the following URL info for the Midland air dryer:
Main website: http://www.hbsna.com
Part numbers etc are available, as well as their "Technical Library" under "Services".
Here are some shortcuts to the relevant documents for my '99 36T. These include exploded views, maintenance schedules, trouble-shooting, etc.
General Info: http://www.haldex.com/North-America/Applications-Products/Literature/Brake--Suspension-Systems-Literature/Airline--Air-Dryers/
There is also an interesting discussion about sagging air hoses. Seems that if sagging the buggers can collect precipitating water at their low points. Not a show stopper, unless it also happens to be winter when the frozen blockage can create an embarrassing lack of air-pressure when you might be wanting it.
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