My 1987 Montero 5 speed tranny is howling and whining in 1st, 2nd, 3rd and 5th gear. Surprisingly, 4th gear is quiet. The tranny is popping out of 1st gear once and awhile if I go down a hill. It also grinds slightly in 4th unless you let the RPMS die down before you shift. The grinding in 4th can't be heard, but only felt in the shifter slightly. The higher the RPM the more grind and resistance going into 4th. Any ideas what I'm looking at here. I haven't checked the oil level yet, but I'm thinking it is OK because 4th gear is quiet. I'm telling you, she's howling pretty good but runs great. She's got 189,000 miles to her credit.