84 300SD trunk lock operation

[OBX Koastie]

I just purchased an 84 300SD from a mechanic who sold me my 85 300SD almost ten years ago. He had maintained the car for the previous owner for over fifteen years. It replaced a 85 300D that was retired due to rust and a bad transmission.

The 85 SD went over 200,000 miles since purchase without a serious issue. Because of minor oil leaks over time, the ball joints, tie rod ends, motor mounts chassis mounts etc needed replacement. So the mechanic told me he had a "like new (124,000 mile), always garaged, serviced by him for the past several years, etc." Sounded good so I bought it. What a mistake. Nothing but problems from the start of the trip home. I've been able to correct many of them but I have a question on the 84 SD trunk lock, obviously.

The vacuum system controls all of the locks when operated from the driver's door lock. My question is, "Does the trunk lock on the 84 SD also control all of the locks like on a 85 300D and SD? I can feel the lock go past the open position when turning it counter-clockwise to open with the key. I don't want to buy the element if if isn't going to do anything the current element does not do.

Thanks for any advice.