Good job. I found that '80s toyota corolla wagon rear springs are the same form and curve as my truck, so I just cut down the longer leaves to length, and replaced a couple of broken leaves.
I'd say one of your springs was slacker than the other, tipping it out of balance under pressure. The leaf springs have a lot of work to do on the front. Note that the centreline of brake torque and leverage, the spindles, passes directly through the spring centres to minimize twist. And I think that the springs normally sit fairly flat, to deliver the brake forces cleanly through the spring to the rear shackles and avoid more bending and twisting.
So the new ones probaly have a far easier go of it.
