I have a 1996 F250 4x4... to set the timing you have to first remove a chip out of a harness clip, mine is up by the firewall on the 1996 (I have a 1989 too and the part you remove on it is right by the distributor). On the '96 you look where the harness goes through the firewall, under the brake master cylinder.... there will be a clip with a rectangular grey chip in it.... the chip is about 1inch x 1/2 inch x 1/2 inch. You take that out and the computer quits trying to control the timing... then just do a regular timing job... mine is 10 degrees BTD. The timing chains on these are known to stretch and my timing was off by 10 degrees with 140k on the motor. Talk about improved performance!