Joseph,
I am glad you got the replacement agitator. The splines on the agitator shaft are heavily rusted, as we had feared.
To properly rebuild this machine, here is what I would do:
1) Remove the transmission. You need a replacement or a new agitator shaft for the old one. They can't be re-used with rust on them like that. If you strip the rust, the remaining material won't be sufficient to drive the agitator without slipping and stripping the agitator.
2) Remove the outer tub. There are lots of reasons for this. You need to strip and protect/paint the center post. The best way to do this is to have the tub out. You also need to replace the center tub gasket before re-installation.
3) Replace the upper center post seal. The center post is rusted up to the top, indicating that moisture is coming up way too high, which is why the splines rusted.
4) When the tub is out, you can carefully inspect and clean it. I am not sure if what we see on the tub bottom is iron stains or rust, but quite often, most of that will come off. When the tub is out and cleaned, you can paint if with POR if it is deteriorating.
5) There is probably rusty build up in the basket centerpost. Clean that up too --- you may want to POR spots there as well.
6) When you're doing all of this, replace the agitator seal on the spin tube. It too will be worn and will work together with the centerpost seal to create an air tight seal under the agitator to prevent moisture from rising up the center. A healthy machine keeps moisture about an inch above the rubber center gasket.
I hate to tell you this, but some of these steps are likely to be "not fun". We'll help you through them, one by one.
Gordon