what would cause a 8 sec ladder bar car head left off the line, next run head right, ( hard) have not looked yet, twisted housing or bad shock? thanks in advance

What rear end?

9" ford

I would start with a real close inspection of the entire suspension both front and rear. Look closely at all mounting points, checking for cracks or anything worn or in a bind. Then maybe find some scales and see what you have there.

I’ve seen a binding shock do this.

going to scale it this weekend

Make sure your rear end is square also. If it has some rear steer, and the opposite side is preloaded, it could potentially do what you are saying.

Absolutely, check for broken shock, binding or broke rod end, check all the welds on the ladder bars and housing. Check your track locator / wishbone for anything broke, loose or bent. You could put car up on jack stands an raise and lower rear end with and with out shocks checking for binding, twisting or strange movement. Check for any movement in front ladder bar mount including the rod ends there.
Then check the front end, look for loose steering box, play in the box, check your toe in through out range of travel.
And if you have video look and see if it pulls one direction or the other when one or both of front wheels are up.
Also could be rear tires going away, a small tire on a heavy car sometimes sidewalls do not last as long as a big tire car.

I agree that the tires are the first suspect at causing this problem. An 8 second car with ladder bars is definitely working the sidewalls hard.

Had a friends car doing the same thing (not quite as fast as yours) It was the front shocks were junk. If you jacked it up and let it down fast, it would settle differently each time and it was steering the car on launch.

Just my .02.

Sidewalls giving up on slicks

thanks everyone, tires new, shocks good, 9" housing bent like a pretzel, old oem passenger housing not braced well.worked fine early on until he stepped up the motor

I would check the flexible brake lines one may have colasped.

With ladder bars on a similar type car we found the ladder bar front mounts tearing loose from the frame. Our clue was the rear tires would keep changing location/distance from the outer fenders when parked in the pits.