Early 273 LA bolt on timing marks? 2 kinds?

I've got a couple of 273 engines that I'm working on. I just noticed something interesting. There are 2 different bolt on timing marks.

One shows

0 -
_
10-
_

The other shows
10-
AFTER
-
0-
-
10-
Before
-
I'm assuming the second one is from a newer 273. The 0 is in 2 different places. Perhaps 10º apart. What goes with what? I wish I'd have noticed before I started taking things apart. I incorrectly assumed that there were 2 kinds. Bolt on on the LHS and cast in of the RHS. Apperently there are more options.