I also never realized G1 Wierdwolf had movable shoulder...vent thingies. Not in thirty years did I realize that.
They're missile racks.
Optimus Prime's trailer opens into a sort of "combat deck" with a missile-firing robot and a little launching scout car inside.
Missile-firing? Sure about that?
Maybe "Convoy", but not Optimus Prime, AFAIK....
"Missile" is what I call Roller when fired from my G2 trailer, which is one of the versions that has no stopper on it to throttle the launcher thing.