Remove and install new transmission 904 auto

The above is a good start, a few more

Depending on your shop equipment, you need some way of supporting the engine. Rag padding, a good 2 x 4 across the inner fenders, with chain, come-a-long, or just nylon tie straps under the engine.

Figure a way (small bent piece of scrap) to bend a tab, bolted to a lower dust cover hole, to keep the torque converter in so it doesn't fall out ON YOU, or get fingers. This can also damage the converter snout/ front seal/ etc

You can buy plastic plugs to replace the yoke so trans fluid doesn't drain out the tail, otherwise, round up a spare slip yoke.

If at all possible drain the trans first. On most, this means removing the pan, or at least dropping all but one corner of the pan, then put it back on there.

Make sure you get things supported. Ya don't want to drop that pig on ya!!!