ZF Transmission filters

[birdshill123]

I want to change the tranny oil and the filter in our 88 FC ( ZF
transmission. I have 2 questions.: I think the filter is a ZF
4139298038. Where can I obtain one?? How much ATF will I need? My Blue
Box says the capacity is 47 quarts but obviously you cannot drain much
of the oil. I seem to recall a post some time ago where it was listed
as 5 gallons. Any help appreciated.

Bruce

1988 FC