Tach and Air failure 300D

Well, I found the problem. Both my tach and my air conditioning had quite. (1985 300D). I found the relay under glove box and changed the fuse. It worked! BUT! then it blew the fuse again right away. I had ordered a new relay so I tried to install that. It wouldn't fit because it had an "extra" post. Turns out this post #87, was paralled with another next to it. I used my dremel tool and cut off the extra post (the one in the middle) and it fit AND it now works perfectly. Doug