Hot Rods Using a floor jack to lift a car placed under the 9" ( center Pumpkin

I do know that 9 inch Fords will flex laterally . I pulled the chunk on my avatar and it had marks on the inside of the housing and saw were the ring gear had rubbed the inside back of the housing. Built a back brace and never had that issue again. That was after about 400 wheels up passes leaving off a 5800 rpm stall convertor and a transbrake with a 5.86 gear.
I tried to download a video of the car , but it won't allow it . Would have been good watching for this morning.

 

One thing that I started doing about 20 years ago for hot street cars with 9" rears was replacing the axle tubes with 3" Mechanical tubing. either .125 or .1873 wall thickness. Not as stout as a back brace but it still stiffens them up a ton.

We used to use back braces on our off road trucks in Mexico all the time. Made all the difference in the world.

 

Beamer you have done alot of cool stuff !!!

 

The third member and driveshaft bouncing up and down on rough roads should bend it right back, after awhile it'll work harden and snap into. Watch it.