I can't remember who did the write up, but if you search the archives there is a great "how to" on this subject. I used it the first couple of times I needed to troubleshoot the vacuum system on my cars. Now, I know what I am doing and can do it without referring to this write up. Search the archives and you will find volumes on this subject.

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Mike

'80 300D
'84 300D
'85 300D
'87 300D