I built a 51 3105 panel a few years back and powered it with a 455 Buick, T400 trans, Olds rear end, and
ended up removing the stock springs. I used a Chassis Engineering rear spring kit for AD trucks.
But, keep in mind a panel is considerably heavier in the rear and top heavy.
Even with the new springs the truck had more body roll back there than I thought was safe.
The kit came with a shock relocation kit that moved the shocks inboard. Might be good enough for
A pick up, but not a panel.
Solution:
I re attached the Stock shocks (outboard of the frame) by stacking the original spring plates below the kit plates.
Did not need to remove the new shocks since they were well inboard. The addition of additional dampening on the
outboard side of the frame eliminated body roll and gave a nice firm but comfortable ride. A four shock set up!
Also, a rear sway bar might be an additional consideration, but I felt the truck was riding just fine without it......
Those panels are tall and really heavy so your concerns over rear suspension are justified.
