I agree,
In my experience with these platforms:
I've had 1984 ramcharger, 1989 ramcharger, 1983 Power Ram W150, and a 1988 Power Ram W150.
The 1988 Power Ram did not have a roller LA 360. (it was manufactured in 08/1987 so It's possible it was using leftover 87' stock)
The 1989 Ramcharger did...