Welcome to Allpar. Valiant was the first to use a lightweight aluminum case Torqueflite. It only had to handle the 6-cylinder torque in a light car, so it wasn't a heavy-duty unit. It didn't have to be for what it was intended for.
I think that the A-904 was based on it.
It may have had a non serviceable, but cleanable mesh pick-up screen instead of the modern replaceable gauze filter element.
If you have a pan gasket, I would drop the pan for inspection, cleaning and fresh ATF.