Full of aluminum, rear seal is leaking so I figure it could have something to do with tail shaft. I bought this trans from All State Gear in San Antonio Tx and it was not a good experience. I am willing to spend the bucks and get a really good trans build. Any suggestions?

No Warranty? At one time All State was supposed to be a leader in Dodge manual re-man's. An NV4500 is definitely not rocket science, but aftermarket parts can be sketchy at times.

If you want something you will never have to worry about, a Eaton can be had for the price of a built nv4500 and will take one hell of a beating. 

If that's a bit rich for your blood, I have heard good things about High Gear, but take that with a grain of salt as I have yet to destroy a NV4500. https://nv4500transmission.com/ Based out of Memphis, TN.