I am replacing my opti and stipped out my center crank shaft bolt hole. I had to remove the balancer hub to drill out , tap and install a heli coil. when I removed the balancer hub I noticed no key slot on the hub. (my first lt1) when I install the hub back I guess I don't need to line up anything? also , should I rent a balancer instalation tool.

 

Some people say yes, some say no to whether the hub should be in the same spot. If you didn't mark it there may be a wear mark inside the hub where the keyway is on the crank.
If you rent a pulley/balancer install kit don't rent the mac tools kit as the 7/16 - 20 stud is too short for a lt1 hub. A threaded rod, nuts, washers, and an old bearing worked good for me.

 

The LT1 does not have a key in the crankshaft so that is normal. There is a mark indicating where one of the cylinders is at TDC but, the hub and balancer are neutrally balanced so it doesn't really matter which way you install. You can get just a threaded rod the right thread and make an installation tool if you don't have one.

 

After almost stripping out the threads in the end of the crank of my Impala, I built an installation tool from threaded stock, a bunch of washers, a nut, and some engine assembly lube between the washers.