The trick to reading those dipsticks is to look at both sides there will be one side that has fluid all the way up. The other side will show a level. Always look at both sides the wrong side has no obvious level on it with fluid going quite high. I have always figured it came from riding on the tube which has oil on it.
Based upon the noise before failure you probably have failing reverse clutches.
Bosch Master, ASE Master, L1
33 years MB technician