the dizzy drive shaft should not be able to slip. it can be installed wrong but you have to force it and usually damage the opti. next time change parts one at a time so you can tell what is making a difference. it may be when it died it was something other than the opti like wiring and when you changed the opti you installed a damaged opti. then when working on wiring you fixed the issue but had a bad opti in it. anyways good that its running. so is the trans working right?