Mopar performance leaf spring.

rumblefish360 said
Good question! I will guess it has to do with ride quality and/or the amount produced.

The ESPO springs were pricey at the total. (AKA shipping included price.)
But IMO, well worth it in the end.

Summit prices XHD springs

B body 109.97$
E body 108.97$¸
A body 199.97$

SS spring 112.97$

Go figure...