Hello, I am new to the world of Subarus so please bear with me.  I have  1999 Subaru Legacy 2.2L, Automatic with a bad Air Flow Meter.  My question is: I have a #22680 AA29A meter and all I can find used is the AA160, AA290 or others.  Are these air flow meters interchangeable or MUST I use a 22680 AA29A?  Any help is appreciated.