starter grinding

Rusty… you might be right. I just figured this was a way to run the engine before installing. I had the access to the converter and bell housing cheap.
Think about this for a second. When the transmission is mounted to the engine, the converter (bolted to the flex plate) is supported horizontally by: The pilot on the converter into the crank flange, AND the hub is supported by the transmissions pump. With what you're doing now , with it mounted just to the flex plate, the hub has no support at all. And I personally don't see mounting it to a B & M or any other flex plate will cure the problem. JMHO and others may not agree.:canada: