getting it certified i dont know. older trucks usually weigh more.
4 things you need to tow safely for the basics:
1. truck weight.
2. wheelbase. longer it is the more stable. dually is more stable as well.
3. pulling power.
4. stopping power.
weight is about the permanent weight of the truck. bumpers, frame, body, bed, etc. not adding a couple hundred pounds of sand and saying your weight rating has gone up. if the truck is significantly outweighed by its load (assuming no trailer brakes) the trailer will push you around.
longer wheelbase vehicles are more stable with heavier loads/longer loads when it comes to emergency maneuvers.
power. need enough to maintain speed limits without taking an hour to reach it. usually not a problem with 3/4-1 ton vehicles.
braking ability. BIGGEST factor on older vehicles. need to be able to stop the load in a close to normal distance without losing control of the trailer. trailer brakes make a huge impact on what your vehicle can safely tow.
