Thanks for all the input. Looks like I am in for a rebuild eventually. I might see what some shops around me charge for a rebuild, but I am down to take a stab at it. I have always been apprehensive about tearing into an auto trans, but there is only one way to learn....
Got a few things to sort out:
Rebuild Kit
I see lots of kits available from ebay, summit, etc. Anyone have a recommendation for brand/supplier? I imagine this has been asked many times, but I assume a 727 kit will not work on my 904?
Resources
I have the 1972 Plymouth Chassis Service manual.
I ordered this book:
https://www.amazon.com/gp/product/1613253354/?tag=fabo03-20
@cannucky Is this thread the video series you recommend?
Video reference, TF727 600hp rebuild
I am just in the info gathering stage here, I may make another thread when I begin the actual rebuild.
Keep the good info coming, I appreciate it!