Small Engines (Lawn Mowers, etc.): transaxle service, rubber plugs, canadian model

Question
I bought a used lawn tractor Craftsman(Canadian model) 944.608920 with 22hp Kohler.  Appears to be same as AYP8228A79.  The transaxle has a filter on it. The manual says it is a sealed axle and does not need servicing.  Then why a spin off filter?  In removing old filter about a quart of oil drains.  The question is how much oil/lube should be put int the axle and what weight or type of oil.  
    This does not seem to be a common transaxle on these tractors.  I can't determine if this is a peerless, dana, foote transaxle.
    All input appreciated  

Answer
 Hello Bob:

 The Transaxles with the Filters are Serviceable but Seldom Require any. There should be 2 Rubber Plugs on the Top of the Transaxle Housing on either Side of the Cooling Fan. These are for Adding the Lost Fluid when Changing the Filter. The Oil is SAE 30 Engine Oil. Hope this Helps.

 Good Luck

 Respectfully

 John