Replaced the harmonic balancer on the ‘89. That bolt was tight! I tried putting grade 8 bolts (5/16-18 1 1/2 inches long) in the puller holes to brace the pulley with a pry bar so it wouldn’t move but both snapped!! Had to resort to the redneck method of turning over the engine with the socket on the bolt and the wrench against the frame, worked GREAT. Drilled and tapped two holes (couldn’t drill out the snapped bolts) so I could use the puller then had to go back to the hardware store 16 miles away to get a longer bolt (1/2-20 2 inches long) and some washers to install the new balancer. All good now.