Leaf Spring Plate Casting Numbers

[Gumby]

In the pictures below are the leaf spring plates that I pulled off of my 1973 Dodge Challenger Rallye with 8-3/4" Rearend. I'm trying to read the casting numbers on them and confirm that these are genuine MOPAR parts from the factory. It's part number: 1856-346-7.

According to Mancini Racing, their listing for the repops say that these are the same part for:
1962-1972 A-body with 8-1/4", 8-3/4", 9-1/4", and Dana 60 rearends
1962-1972 B-body with 8-1/4", 8-3/4", 9-1/4", and Dana 60 rearends
1962-1971 C-body with 8-1/4", 8-3/4", 9-1/4", and Dana 60 rearends
1970-1974 E-body with 8-1/4", 8-3/4", 9-1/4", and Dana 60 rearends

Can anyone help?

 

[S Vicious]

Possibly being all share a 3" axle tube?

 

[Gumby]

Possibly being all share a 3" axle tube?

I'm trying to identify the casting numbers specifically and determine if it's a genuine MOPAR part.

 

[Gumby]

SOLVED: A guy from the E-Bodies.org Facebook group confirmed these are genuine Chrysler parts and he sent these photos to support this. The casting number is 1856346 and below that in large letters is AAOS. Next to that is DPCD which stands for Dodge, Plymouth, Chrysler, and Desoto.

Additionally, for the E-bodies, this part only fits 1971-1974 E-bodies. The picture showing the two different plates has the 1970 E-body spring plate on the left compared with the later year on the right.