Not only is the shape different, but the triggerguard on mine looks thicker as well, at least at the edges.
It would be interesting to line up examples of A-types, one from each year, to see the differences.
Another difference between Walt's and mine, not readily discernable in the photos, is the hammer.
Wasn't it around 1988 or '89 when they went to the thinner hammer and heavier firing pin?