The tailshaft seal is different between 65 and 66 904 trans. 65 has the flange on the trans, 66 has the slip yoke. I have been searching online , but haven't found the correct seal, yet. When I get to the shop, I will see if I have the part number for the correct seal, or measure a new seal, and locate one by dimensions. The ones on rock auto are not correct for the 65 904 trans