In reviewing the diagrams for the '85, it is apparent that this vehicle has a vacuum system that differs significantly from the '84 300SD. The changeover valve on the valve cover is controlling the transmission modulation again, something that the '84 does not have.

There is also a "cam plate" with a "valve" attached in the aforementioned diagrams. The '84 does not have this arrangement.

Just a word of caution. The vacuum systems did change frequently throughout the years. The '85 probably has the most changes of them all.