I believe it is .75? The 4l80, which is what will be going in my car is a .75. Couple it with a 4.10 rear gear and you have a final drive of 3.075, very similar to what many of our cars cam with. Only speaking for myself, when I did drive one of these cars all the time, I very rarely if ever encountered a hill that would take an auto car out of drive at 60 mph. That being said, why would it shift out of od if so equipped? Same can be said for lock up, considering that the controller I have allows me to adjust the clutch based on several factors, 2 of them being speed and tps. Could very easily set it up so that at anything under half throttle at 60 mph the tcc stays locked up.
