
I was alerted to this strange intake manifold by our friend the auto designer John Frye, who spotted it on the Innovative, Banned, and Unique Racing Vehicles Facebook group. I see why it caught his eye: it’s a richly strange and puzzling manifold design, and I can’t think of what engine it might have been designed for. I suspect one of you loons may have an idea, so it seems like a good idea to put it out there.
Here’s the post from the group:

It seems to be a triple-carb manifold to feed a six-cylinder engine—a V6? I suppose it could be a straight-six, too? It looks like it’s basically three stacks of flattened intake runners, in funny U or wavy shapes, each fed by a carb.
There’s also this number stamped on the manifold:

H-403-A? I think? Does that ring a bell for anyone? 403 could refer to an Oldsmobile 403 engine, but that was a V8, so I don’t think that’s it.
It’s a really odd design, so I’m quite curious, but also quite stumped.
So, one of you greasy-handed car dorks out there must have some idea, right?
Let’s see if our big, wet, pulsating collective brains can help out! Gimme your ideas and theories below!
DISCUSSION
This one looks like a crab going “ohhhh” or a spaceship with its thrusters pointing down as it makes a landing. Possibly ships from a crablike alien species.