904 shifting weird

Does this trans. have a modified manual valve in it? If not there's no possible way it checks the same level fluid in park and neutral because in park it bypasses and neutral it charges the circuits so it'll always read a lot lower in neutral. The only case being if someone has installed a modified manual valve in the valve body to make it pump in park. After warm up or a drive I'd recheck after it's idled in neutral for a minute or two. My guess it's just low on fluid