As I get closer to my 56 being a driver, I've run in to a problem. I've got a 350, 700R4, 3:42 10 bolt in the car. The 700 was built over 10 years ago, and sat dry on the floor until I installed it in this car a couple of years ago. Lately, I've left my shop and drove it down the road a couple of miles several times. At first, it was late shifting an harsh. I've added some Seafoam trans additive to it. It now shifts smoothly 1-2, and 2-3, but I've never had it shift in to 4th, ever. Before I burn it up, any suggestions? The guy who built the trans has checked the TV cable and says I have it set right. He says he'll come check it.........maybe the governor?