ha ha. I have had such a time dealing with this problem.
in my 87 olds -
I know that every engine bolt I have delt with was metric. I also know that some of interior bolts and screws seem to be sae but some are clearly metric.....well who knows.
with my 89 bonny the engine was metric and around 75% every interior or non-engine bay screw/bolt was sae.....or so i thought.
to answer your question I would imagine all drivetrain and engine WOULD BE metric as I dont see gm doing something that crazy.
but with how often they swung back and forth in the eightys.........