Coolant lines? Shift linkage? could also be the rear or front seals leaking
There are several things that can cause your 1986 Nissan 300 automatic transmission to send you a start leaking fluid the most common cause is a blown seal in the front of the transmission. There is a seal in the rear of the transmission. The transmission pan gasket can be leaking.
Low Transmission fluid
Replace the gasket on the transmission pan and insect the seals on the transmission where your driveshafts come out
if you have an automatic transmission there should be cooling lines going to the radiator to cool the transmission fluid the lines could be leaking or the tank could be leaking
Usually automatic transmission fluid is a reddish color. If you see red fluid on your driveway, then you probably have a transmission leak.
Failed speed sensors, leaking cooler lines, or a leaking solenoid pack.
That's automatic transmission fluid , or power steering fluid , so it would depend on where it is leaking from
Obviously a seal has failed.
Where is it leaking from? Could be front or rear seal or coolant lines Did you change gasket when you changed fluid?
The better question is what is leaking transmission fluid?
Because your transmission has a seal that is leaking.