Also the breather with threads for a sender is used on the '84-'89 3.2 to activate the heater fan on top of the engine. Also the 930 engine has a thermo valve installed in the breather.
Get an earlier magnesium breather cover to save yourself 4 ounces?
I don't know if that's the actual difference in weight. But I do know they're light as a feather (I have one on the shelf).