It's also a press fit going back on. The outer ring of the balancer is held on to the inner ring with a rubber type material. If you pound really hard on the inner hub driving it back on, you can separate the two pieces destroying the balancer. GM used a special holding tool that held both pieces as one.
To help installing, you can heat the balancer to 200 degrees with out worry and if possible cool the crank using dry ice or set the engine outside in the cold. When you have everything ready, hammer, brass punch, gloves, etc.....
in one quick motion, align the key way and shove it on, then quickly tap the center hub to seat the balancer to the timing gear and crank shoulder. If all goes right, you should be able to get it 75% or more on the first stab. Be sure to clean the two surfaces really well and remove any burs or rust.
A second option is to drill and tap the center of the crank and use a small block Chevrolet bolt and washer to pull it on and hold it there. Any machine should be able to drill the crank or you can do it yourself with a hand drill and sharp bits. The crank is fairly soft and drills quit easy. Being dead center is not required but you should try to be as close as possible.
Joe
