Well, either those springs have been modified/repaired, or they're not original. Every leaf should have the rectangular "pocket" at the end, and tapered (one of them appears to be just cut off). Also, the clamps (also known as straps) don't look original either. I agree, I think someone took an original set of 4 leaf springs and added another (incorrect) leaf!
And I'm assuming you mean a 3.73 gear, not 3.37, right?
With the factory multi-leafs.....was the main spring a dual taper (width and thickness) like the mono leaf, or was it a continuous width along its entire length
Mike, the only taper is at the end of each leaf. Approx the last 2 to 2.5" inches. The rest is all one thickness and width.
Ed