Start the car. With the engine running on idle, put your finger over the two vaccum hose bibbs. The one with zero (or almost zero) vacuum will be above the throttle plates (ported). The one that tries to put a hickey on your finger is manifold vacuum.

Or, you could use a vacuum gauge.

Take a look at these links:

http://lists.twistedpair.ca/pipermai...il/029574.html

http://www.chevyhiperformance.com/howto/97438/

- my great, great grandfather carried a Henry with the 7th Illinois Infantry in the WTBS, therefore, the handle.