A904 transmission for 318
If push comes to shove, consider going to the Mopar show in Carlisle, Pa. The earlier the better as tranny builders will buy up the cores or they send scouts to do so. There is also a guy on FB Marketplace in Carapolis, PA (just outside the Pittsburg Airport ) who builds Mopar transmission on the side. I went there and bought a 600hp capable trans. He was regular rebuilds as well