It will shift into high around sixty plus mph , and it will shift hard , Hoss429 , 74 pinto wagon and lugnut are right , you are missing engine vacuum, and more than half of the leaks I found on ALL the cars using the C-4 is the rubber elbow that goes to the modulator to the steel line at the bottom , over the years it get oil covered and turns to a goo or swells up and falls off , or splits , and it can happen on the top also, valve cover leaks and does the same thing to the hose there , good luck, and have a great 4th