I have a set of pistons that I don't know how produces. They have a dollar sign underneath on one side and B571 on the other along with a 51 in another spot and a "B". This is all on the underside of the piston along the skirt wall. They also have a 030 (.030 oversized) on the head of the piston face.

They are a set of 4.155 pistons for a 400 small block chevy.

I've done searches on google with all sorts of combinations but nothing that really lead me anywhere.