I bought my first 450SLC from EBay and got ripped off bad. The dealer sold it to me as a drive accross the country car. Just get in and drive. Ya right! The engine smokes, knocks, drips and leaks, no a/c, heater, radio, steering has three inches of play at the wheel and the list goes on and on. I have many vacuum leaks and have fixed most all of them with a smoke tester. I see a vacuum trunk opener in the trunk behind a panel while checking for all vacuum leaks, and can not find the control to open the trunk in the cabin. Do you know where it is? What it should look like? Maybe it has been removed by the previous owner. I am a new owner of Mercedes-Benz and find an over engineered clustor of items in and behind the dash. Got a repair manual and have started to restore this old girl. I have had a shop charge me over $1.5K just to fix the A/C that quit working the next stop light. I found an old school mechanic that only charges $55 per hour and has fixed all the mistakes the first shop broke during the test. I will get even with them with all the documentation old school has done. So any help is greatly appreciated because I have exhausted my savings account on this old girl.
The opener should be on the door panel if it has one. It sounds like that is the least of your worries. I couldn't agree more with you are far as over engineering. They are great vehicles when they work, but when they break, you need to have a lot of money. Many of the vehicles of this caliber are the same. They are great when they run, but when they break, you'll wish you had an American car. Much cheaper to repair.