How do I do a complete rebuild of my transmission?

Hello,

There are many components that can be replaced during a transmission rebuild, depending on the issue at hand.
A typical rebuild includes all the gaskets, seals, gears and solenoids and other typical worn items. Also, the filter and any screens that go inside the transmission.
So, it will all depend on what issue you are trying to fix.
There are a few special tools that you will need to get this done.
Look below for all the special tool requirements and I have attached transmission disassembly instructions below for your reference.

If you are looking for any specific part disassembly and reassembly just let me know.

Thank you.

https://www.2carpros.com/articles/how-to-remove-an-automatic-transmission-rwd

Do you have any pictures of the part that fell out?

It looks like a retainer but deformed. Can you tell where it possibly came out of? Check the valve body retainers for the valves.

You mentioned that you have issues with slipping, which could be due to worn gear and or torque converter. So, a rebuild of those components is likely.
You want to get a rebuilt kit that has all the regular components, like the picture below.

You should be able to replace the springs, as they are just worn. You could replace the case if you chose to especially you are already in. But it shouldn't be necessary.

One thing you can do is to install a new spring and see the fitment. If it is loose, then the case will need to be replaced. That way you are taking action based on what is required.

You should be able to remove the exhaust hanger bolts, that will give you enough room.

I went ahead and attached the transmission replacement procedure below for your reference.

The retainer just keeps the converter in place. So as long you can do it any other method it will be fine.

Yes, it might make it little tricky to keep it on a stand. But you should be able to get the job done.