It is easy to get the master spline off even one tooth, GM finally figured this out and changed it a few years later and it was installed by aligning a dowel and it would only go in one of three places on the optispark. The easiest way I found to make sure it was right was to put the small driveshaft that goes into the optispark and in the driven gear in the timing cover by itself. If you put a mark on the end of it to reference the master spline you can look before you put it in the cover and know about where it should go, then move the driveshaft until it slide in easily into the cover and you will have found the right spot. Now turn the crank until that spline is pointing straight down or straight up, turn the optispark main spline to the same point and GENTLY do the same with the optispark as you did with driveshaft to make sure it is in the right spot. With everything aligned correctly it will all go back together very easily, if not you will be applying a little force and that is when you have screwd up and got it off. If you need more help PM me and I will be glad to help. I ran in to this when the lt1 first came out, figured out the trick, then about 6 months ago got one and messed up, then remembered the trick, so I have been in your shows on this one.
