I've got a 1992 SE with an AT and here's what happened:

I changed out the transmission filter, what fluid drained, replaced the pan/gasket. It was on front ramps during the change.

Well, when I tried backing it off the ramps, it would not shift. I rolled it off, added fluid, but still no shift. I get it hot, run it through the gears via the shifter, but no go. Check of gauge shows full.

Any ideas guys?

This one's weird. I'm racking my brain to no avail.

My fear is an internal problem with your trans. Problems after fluid changes usually indicate a clog, a failed internal seal or failed solenoids in your transmission.

When you say "full," are you checking the fluid on level ground, in park, with a hot engine? It should be between the top and bottom marks. Overfill can cause issues as well as underfill.

Yes, level, hot, in park. I've read that the reading might not be accurate as the fluid may be drained from the torque converter a bit. I was crazy careful in the process. I'm going to take the pan off again, replace the filter/gasket. I'll check to make sure the o ring is seated properly. I read overtightening the bolts going through the filter could cause an issue, so I'll make sure that isn't the case.

Of all the projects I'm doing on this car, I didn't think a pan drain, filter replacement would lead to this debacle.

thanks for commenting