Torque Boxes vs. Frame Connectors

after a lot of set backs
we finally got the 449 small block finished

found out the rest of the car needed more attention
stock wheel well 26 x 6 slick

went to a tracks last night of racing (season end 2013)

never could get any traction
shook the tires so hard
the passengers window mount , the window fell down inside the door frame. lol

was good to find out
-6an lines from reg to carb to small
needed more tire

1st attemp of the night

so this winter
installed frame ties
moved the springs in
move the axle forward 2"
change to 25" front segment springs
10" wheels with et 275 pro

also installing a roll cage thru the floor
into the frame connectors

So what do you think was the root cause of the tire shake? Were the leaf spring bushings worn out? Was there an excessive amount of frame flex? I've never had trouble with a Mopar having a wheel shake (or hopping) problem. I'd always heard that the design of a shorter leaf section in front of the axle prevents it.