i can find either the fill or drain plugs on my 91' automatic transmission. are they the square ones? any help would be appreciated.

 

according to the Haynes repair manual, the automatic trans dpsitck is loacted at the rear of the engine compartment. if additional fluid is required, add it directly into the tube using a funnel. I'd becarefull though since it says overfilling can cause foaming and loss of fluid.
hope that helps...

 

oh yeah, i think you'd have loosen the transmission pan and carefully pry it open with a screwdriver, allowing it to drain. and if you're also replacing the transmision filter, remove the whole thing and the filter is mounted inside the transmission.

 

You can use an oil extractor to siphon the old ATF out of the dipstick.

Or you can drop the pan, wear a gallon of ATF, and change it that way.
While you're at it, grab a filter kit at your favorite auto parts stores.

Another method is to disconnect ATF cooler line, aim into a bucket, start vehicle, and fill the bucket until the flow is inconsistent or blows bubbles.
Then you could either refill through the dipstick or drop an almost empty pan and do a thorough service.

The filter kit will include the pan gasket that you will need, the filter, and the filter seal if needed. Plus, with the pan off, you can clean it and the magnets.