Truck uncontrollable after bump.

My M51A2 runs good. Still has the old NDT tires and everything else looks stock. The dog bones look ok, no separation. When I first got the truck the truck would do the same thing, but I believe it was caused by tire pressure being low.

I was traveling roughly 45 mph and hit a bump in the road. Pine tree roots has pushed up a high bump and I hit it with the left side of the truck. Only thing I can do is take the truck out of gear apply the brake and hang on for the ride. I am bounce so hard, I have to hold on to the steering wheel to stay in the seat.

Any suggestions?

Assuming I'm understanding this correctly that it is a bouncy bounce (up and down) problem, and not a death wobble (steering left right left instantaneously) problem, I am going to say it could use some shocks ?

Sounds like “death wobble”, jack up the front axle and see if there is play in the knuckle king pin bearings.

If it is bump steer turning into death wobble you more than likely have some well worn steering components trying to deal with old hard out of round tires .

Have someone move the steering wheel back and forth just taking up the play in the steering while you stare at all the moving parts underneath, the parts that don't move near as much as the part hooked to it are typically your biggest culprits, start with repairing those parts first and go from there .

Why make asking for advice so difficult?
You hit a bump?
OK, So immediately after that, WHAT was the ONGOING problem,? IF any problem WAS ongoing or recurring at all.
If I hit a large pothole in my M62 Wrecker it shakes violently from side to side! And I MEAN shakes.
I avoid potholes. (As) All else in the steering is fine and correct.
Check all else in the steering, and make sure components are adjusted and correct.
My Willys jeep does the same sometimes, We are going to replace the steering centre pin and the steering track rod ends to cure it.
Large old vehicles are somewhat notorious for the "Death Wobble" syndrome, Which is violent shaking of the front wheels.
Your Vehicle should not be experiencing 'UP and DOWN' oscillations.
If your truck is driving and steering correctly now, It is rather unlikely you will experience (The 'death') Shaking unless you drive over a large pothole or indention in the road.
But, as said, check all components for slack, free play, and adjustment.

The steering is going left and right, but it is more of a bounce to me. Up and down. I can hold the steering wheel, but I am bouncing hard.

It is hard to explain. But it is so severe I have to almost completely stop the truck for it to stop. It has did this before when the air pressure was low in the tires. Today I hit a large bump in the road on one side of the vehicle and it did the exact same thing. It is so severe, I had a heavy 20ft chain on the tool box, that was pushed off to the front.

holley68 said:

The steering is going left and right, but it is more of a bounce to me. Up and down. I can hold the steering wheel, but I am bouncing hard.

It is hard to explain. But it is so severe I have to almost completely stop the truck for it to stop. It has did this before when the air pressure was low in the tires. Today I hit a large bump in the road on one side of the vehicle and it did the exact same thing. It is so severe, I had a heavy 20ft chain on the tool box, that was pushed off to the front.

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I thought your problem was interesting. Even brand-new civilian Jeeps have reported the "death wobble." Reference:
https://www.roadandtrack.com/new-cars/a28700728/jeep-death-wobble-fix-jl-wrangler/
https://www.extremeterrain.com/wrangler-jeep-death-wobble.html

It mainly has to do with solid axle suspensions but I do think you have some steering components with excess play that you need to hunt down and replace. There is a pretty lumpy, dirt parking lot nearby that is open on Sundays, so out of curiosity about your problem, I blew through it in my M813 at a bit of speed. Aside from the expected bouncing in my seat, the steering was well behaved.

I haven't owned my truck for all that long, and it's far from meticulously maintained. So, if my old truck did OK, then you probably have something needs replacing.

Do what Valley Rock suggests, and have someone wiggle the slop out of the steering wheel while the truck is shut down, and observe steering components that DON'T move that probably should be moving. Also look for anything bent or broken. Check the steering shaft to the steering box and it's connecting joint.

Thank you for the clarification, And yes, You are experiencing the deadly "Death Wobble".
It is a difficult problem to overcome short of a complete steering overhaul.
I have known many jeeps experience it, (Including mine)..Not such an easy fix with heavier vehicles. (As) trying to check the components is no easy task without the proper equipment.
As an initial guide, keep the tire pressures at correct pressures. Look to the steering box free play. Check tow in.