I installed Apc 2 1/16" Blackout Series Vacuum Gauge today instead of dead clock. For $15 new it gives a lot of entertainment and it is showing steady 21" at idle which is calming ;)

I put a T on the manifold vacuum port to ignition control unit and used a copper tubing to get through firewall via rubber around main harness on the driver side. Next time I will be on the junkyard I will pick up the port and install it in the space of the plug to get rid of the T. The vacuum port turned out to be 7/16" ?

At first I put a T on the tube to oil trap but it read only 10". What is the purpose of having both manifold and ported vacuum on oil trap anyway?

Here is a nice article I found on vac reading interpretation
http://findarticles.com/p/articles/mi_qa3828/is_200108/ai_n8978956/

My wife though got suspicious of that LED lighted gauge which swings widely when you change gears ;)). I understand now why they do not put them on new cars anymore ;)

Serge