I just noticed today a difference in the case on this '85 I'm working on and my '86 motor. They have the same casting number but on the '86 the left half of the case sticks down further on the bottom than the the right half. On the '85, the case halves are even at the bottom.
This is a picture of an '86. The red lines trace the case profiles. (The left case half is on the bottom.) As you can see, the profiles are different. I just thought they were all that way until today.
-Chris