It does not have one. You must get a big catch pan/ drain pan to catch all the fluid when you remove all the small bolts that holds the drain pan to the transmission.
on the side of the transmission
The drain is near the bottom of the radiator on the drivers side of the car.
My 1990 Chevy celebrity does not have a drain plug on the transmission pan. Your car probably does not have one either. You could break loose a transmission line from the radiator and add fluid in the dipstick tube while the car is running until the color of the transmission fluid clears up. I am guessing you are trying to change the transmission fluid. This is how I changed my transmission fluid there are lots of videos on how to do this on youtube.
According to one source I found the weight of a 1989 Chevy Celebrity varied between 2751 to 2928 pounds. Actual weight of a given car would depend on engine, transmission and other options.
The petcock on a 1989 Chevy Celebrity is at the bottom of the radiator on the drivers side.
The oxygen sensor on a 1989 Chevy Celebrity is located in the rear exhaust manifold on top about the center.
NO it will not.
The spark plug gap for your 1989 Chevy Celebrity 2.8 V6 is .045".
Looking in my factory service manual for a 1989 Chevy Celebrity I found no reference to an accessory relay.
The 1989 Chevy Celebrity V6 is rated at 130 hp.
The radiator drain plug on a 1989 Chevy C1500 Silverado is on the bottom of the radiator.
Yes, it should bolt up.