About a hundred years ago, or maybe it was in the late 70s, while working at Austin-Healey West, we put a set of springs on a customer's BN7. I don't think anyone in the shop had ever seen a *new* leaf spring, so we didn't figure out how wrong they were until the job was all put back together.
Maybe we should've had a clue when we had to use a Porta-Power (between the eyes) to spread the spring out flat enough to meet the mounts/shackles? Or possibly when we had to use some GIANT C-clamps to squeeze the spring up to the axle perch? But we didn't, and the back end sat as high as it could, with the axle firmly pressed into the rubber pads on the frame.
Maybe it'll settle, we thought? Nope, not gonna happen, but I'll never forget taking it around the block to test it; totally rigid suspension, with the rear tires skittering over the smallest pebbles, and QUITE LOOSE. Diabolical, really!
Nearest we could figure, was that the springs they sent were for a BJ8/PII, so the correct set was ordered up, and we had to do the job over again. This time, we were much more successful!