BO29 and LO23 Hemi Blocks

BO29 and LO23 Hemi Blocks

Does anybody know or have an original block From 68 BO29 Hemi Barracuda or a LO23 Hemi Dart.
My question is, What is stamped on them. Was the first 50 different from the rest?
Trying to find some info on these blocks. I am going to look at one. I want to make sure what I am looking at.

thanks for any help