I have a 1957 special with dyna flow trans. When running it has no leaks but sometimes, not all the time, after driving it will push trans fluid out of vent tube by driveshaft and also push it right out the dipstick tube. At least a quart and maybe more. Sometimes it doesn't happen. The car is new to me. It shifts fine when running. After it pushes oil out it will be mushy at starting like it lost it's prime or the tourqe converter emptied. It would seem to be boiling over maybe after it stops flowing when engine is off. The lines to the radiator cooler are there and hooked up. It doesn't leak when parked and left running. Any thoughts? Thanks in advance.