Shouldn't be afraid to buy 6-7 quarts of quality trans fluid, drop the pan, pull the filter and replace with the new Purolator or whatever brand you bought, and reuse the trans pan gasket and button her back up.
You will have replaced about halfof the fluid. If there is sediment or coating in the trans that will slowly start to redissolve with the fresh additives. I'd suggest then dropping and changing fluid again after 6-10K miles again without replacing the filter--unless you felt the old fluid was carrying lots of goop and that may have partially plugged the new filter.
When you drive a couple thousand after changing you'll know if there'* any effect or not. I changed mine at about 85 K three times in a row. That means a very small fraction of the original was left but the shock effect of all new fluid during a flush wasn't there. Just new fluid, then more new fluid, etc., increasing the ability of the fluid to pick up gunk that was in there.
Dual auto air on both