727 Locked up while driving causes?

My own personal experiences with TF3. I need to say that I have never heard anything else bad about them. It turns it into a full manual automatic.

Experience 1 - my 72 dart with warm 440 and 2800 to 3000 stall converter, 3.91 gears, vintage 78 transmission, non lock up. I am a fairly competent guy and have worked on transmissions my whole life. I installed the kit to a "t" as outlined in The instructions. The first outing with the car, I was standing in front of it, running and in park. I was setting the timing, had my light going and reached back to the carb and opened the throttle to watch the advance curve. Somewhere around converter stall speed the car came alive, jumped the park pawl and came at me. Shifter still in park......I rode the front bumper for a few feet until it pinned me and crushed my right femur.

Experience #2, my buddies duster race car, 440, fresh transmission with tf3, everything seemed fine until he made a few passes, then for no reason coming back down the return road it completely locks up the rear wheels as you describe. After screwing around bit it starts to work normally again and there are no more issues for two seasons.

Experience #3 - a good friend of an acquaintance of mine has a fully restored super bee, 69 or 70, with a warm bigblock and tf3 in the 727. The transmission was professionally done in a good shop. They also installed the tf3. He is sitting in the car, in his garage, running and in park. He brings the revs up and suddenly the car pushes through park and ends up going through the back wall of the garage. No one is hurt except the car and garage.

That is it, all I know. Like I said I have not heard any other bad experiences. It could just be me.