1964 Stepside frame help

[64chevmn]

I just purchased this truck last month and I'm still finding lots of surprises the previous owner left for me. On a crossover member on the frame where the drive shaft passes through and the rear trailing arms bolt to, I think the PO left me another surprise with a few chunks of flat steel that appear to have been added. I'm assuming with the high horse power engine the truck has, was he trying to stiffen the frame or keep it from twisting??