They sound like a M-80 or Silver Salute going off under your car accompanied by fast drop of the affected front side of your car.
Be careful handling the as the broken edges will be extremely sharp.
What size are those?
Did Dodge Vans use torsion bars? If so I heard one break under load 20 feet from me off a sidewalk. I was walking and this van drives by and BAM! sounded like a gunshot. I wince and then see the van start to pull over fast. I walked up to it and the driver tire was up in the well.
