40 Ford truck helper springs? What are these?

These came off of a 40 Ford truck rear end. The best I can think is, maybe they are helper springs? Should have taken a picture before I took everything apart -coulda, shoulda, woulda.

The spring mounted directly over the axle. It was spaced on each side with oak blocks between the axle and spring shackles. The yoke shaped piece fit aroun the bottom of each axle houseing, with the tail end of the yoke propped against the banjo housing. Seems to me like it would have put a lot of unwanted stress on top of the axle housings and the bottom of the banjo, but maybe that's how it was done??