65 273 Intake manifold

wheelsport said

The intake bolts are 5/16". The casting number underneath of the manifold is 3475 & on the top left front S-P 2-P 318 is cast on the top of the runner.

Click to expand...

A pic would be nice-
Is it like this?

If so, you've already got an aftermarket (Edelbrock) 4bbl. manifold, if you have a 2bbl carb on it, it must be using some kind of an adapter plate.

And if you do have the 5/16 intake bolts, it must have been modded already...?
A factory manifold would be cast iron, an SP2P is aluminum.