8 quarts is usually in the ballpark range.

ATF+4 is a completely synthetic fluid so just make sure its got the licensing # on the bottle and you'll be fine. I have poured everything from Mopar to walmart branded atf+4 into our fleet and besides the price difference the bottle sure looked identical...

If you've got the 4.7 then make sure to get both filters for the RFE transmission. Most stores sell them as a packaged set but others sell them individually.