S/S Spring question

I posted your spring's numbers over there.
We'll see if anyone recognizes them.

According to the parts books, a 383 would get spring pack p/n 2808 677 which used main leaf 2808 678. Only 383 springs use that main leaf. (maybe in '69 440s did too)
According to examples posted, those springs were stamped xxxx 056

Interesting that Stengle Bros replacement shows both the part number and the stamp number.
78-581 Leaf Spring Assembly

Some comparisons can be made with this chart
Dodge Lancer Dart and Swinger Leaf Springs - Stengel Bros Inc.