Is it BO and LO or is it B0 and L0….that is the question??

I own an original 68 Hemi Dart and have seen the VIN's on dozens of L0 and B0 cars. I was told by Tom Hoover at the Mopars at the Strip show a couple years before he died that they wanted to make sure the Super Stock cars had a unique VIN. I have never seen any Chrysler documentation on this issue though. The only docs I have from Chrysler talks about the sales codes but does not mention the actual VIN...

Hemi Dart document.jpg