You are looking at about $1200 for everything if you plan on beefing up the c4 instead of using the stock parts for it. You might get everything for a bit less or more, but I would say that is a generally fair price.
First, you are going to need to take off your h pipe at least, I went ahead and removed the mufflers back as well. I loosened the headers from the block too, this would most likely not need to be done if you have a shorty type header, but with longtubes, you are going to need to move them around to get that big AOD bell out, and the c4’s bell back on.
You can now drain the fluid from the AOD, but I didn’t even worry about it. Take the drive shaft off of course, the bolts in the rear are a pain to get off(we had to torch one bolt before it would loosen), and we supported the back of the tranny with a jack. Next, we went ahead and took off all the wires on the AOD, and we pulled off the kickdown cable(I am using a manual valve body, so no need for it).
We went ahead and loosened the bolts on the bellhousing, and took off the metal shield on the bottom of the bellhousing. You should be able to see the flywheel and converter inside the bell once that plate is off. Then, you need to disconnect the converter from the flywheel. What we did was put a ratchet on the crankshaft up front, and turned up there until another person underneath could see one of the bolts on the converter/flywheel. Then, we would loosen that bolt(might have to apply pressure the opposite way on the crank from up front again while another loosens the bolt), and repeat that procedure.
Once you get the converter disconnected from the flywheel, you might wanna get a jack with a small piece of wood on top under the transmission pan, and then take off the two bolts on the ends of the crossmember, then take the bolts off of the bellhousing. At this point it should be ready to come off, and you will most likely want a helper. You might have to pry the bell away from the block with a crowbar; I know I had to. Once its broken loose, you will want to walk the tranny back using the jack that’s underneath. If you have longtubes, it will take a little work to get it down, just be patient, and you will get it.
Once it is out, you might want to go ahead and change the rear seal. Also, if you get a small belled c4, go ahead and take the flywheel off, it will be too big.