I have a 1975 Olds Delta 88. It didn't come with the economy fuel gauge option, but I found one and I want to install it in my car. I need to know what do you connect the hose that come from the gauge to make it functional? I know it needs some kind of vacuum to it for it to work. Any help would be greatly appreciated.

Thanks a lot,
Carnell

 

Connect it to one of the manifold vacuum ports on the intake. You may have to tee it in. I don't have my 75 shop book handy but the diagram is in it.

I'm thinking you have to change out the speedometer face for this installation if the car did not have the vacuum gage originally.

 

Yup, what rocketraider said.
The gauge was part of a special dash cluster. I borrowed this pic from Ratchetmaster to show you what you're looking for