My 67 dart I put in a 318/904 from a 78 lebaron. Didn't touch the trans. Just new filter and fluid. Been driving it around a couple months and everything has been working without issues. Now 2 days in a row transmission acted funny both times was after it had been sitting over night. I left the house going down the road it would not shift out of first gear. Couple times i tapped the gas and it just reved like it would be in neutral as I was going down the road. After about 5 mins limping it back home I stopped checked the fluid. Fluid Level is right on the full line dose not look or smell bad went to drive it again and it shifted and worked like it should even after making a couple stops ran just fine. I'm wondering if it's the converter giving out.
