OK I HAVE A 97 GMC SIERRA 2500 4X4 WITH A 7.4 454 135K MILES NOW...

SO WITH NOT MUCH ENGINE GUY EXPERIENCE CAN SOMEONE TELL ME WHAT HAPPEND AND ALSO HOW TO MAKE THIS NOT HAPPEN AGAIN...

LONG STORY MADE SHORT...
DRIVING, TRUCK DIES, TOWED 300 MILES, ENGINE REMOVED, DISTRIB GEAR HAS BEEN SHEARED ALL THE WAY DOWN ON ONE SIDE, TIMING JUMPED 180 DEGREES, NEW TIMING CHAIN, NEW DIST,CAP, ROTOR, PLUGS,
ENGINE IS NOW STARTING AND RUNS LIKE YOU KNOW WHAT,,,
CHECKED CODES STILL OFF 42 DEGREES

ANY IDEAS COMMENTS WOULD REALLY BE HELPFUL
THANKS