Cant get harmonic balancer back on, do you really need a special tool oh its a 1991 chevy blazer 4.3liter

Im not sure on this one but i have worked on pressed in balancers and slide on, the slide on have the key way and the press on dont, the balancer can go on anyway, theres no tool, clean the shaft with some emery cloth and the same for the balancer, then if its press on just slide on the crank or hold on the fornt of crank and use a hammer to get it on enough until the bolt can screw in a few turns, then you will use the bolt to drive it back on the crankshaft, an impact gun would do the job. if you dont have a gun then you will need to have someone hold the flywheel with a prybar, stick ythe prybar or big flat head screwdriver into a tooth on the flywheel and lock it form turnning and then tighten the crank bolt until the balancer is on. good day. also apply some permatex to bolt before threding it in to avoid oil leak. good day.