Understanding Block Stampings -1968

1968 blocks drive me batty. Looking at a few 440 blocks. All are 68 vintage Some are stamped PT440S "S" I assume means special. the others are PT440P I assume "P" means premium. My question is should 68 R/Ts have the PT440S and also have a partial vin stamped on the bell housing? or can they have PT440S and no vin on the bell housing? Better yet can they have PT440P with a vin or not?? and both say HP on the upper pad!
[img:center]https://imgbox.com/JOMMEm7g[/img]

[img:center]http://imgbox.com/MEql2ZV8[/img]

all '68 440 "require" PREMIUM fuel

PT440P "premium" = 350hp (C-body engine) with NO partial VIN stamp
PT440S "special" = 375hp (HP stamped B/C-body engine) with partial VIN stamp

got pics of the top pad stampings?

The motor stamped PT440P is currently at the machine shop.Should have a picture next week. Here is the pad from the Charger R/T. The zero is missing from the date.

[img:center]https://imgbox.com/ajXLP8Jm[/img]

[img:center]https://imgbox.com/7RsWBfBZ[/img]