Jack.  I went looking on eBay and found a 3x2 Edelbrock intake manifold for a '54 Ford / Mercury application.  Dennis is right.  The casting number on the intake is 354, the same format as you found on your 357.

Click the link below to look at the eBay listing and the seller's pictures of the Edelbrock 354
https://www.ebay.com/itm/Edelbrock-354-Y-BLOCK-1954-Ford-239-Tri-Power-Intake-Manifold-TriPower-3x2/183390150347?hash=item2ab2e79ecb:g:mV4AAOSw88RbLAui

Looking further on eBay and to add to this discussion of Edelbrock casting idiosyncrasies is this pre-1957 3x2 intake manifold with the casting number 553.  Click the link below to see the eBay listing pictures for this Edelbrock intake with the casting number 553.
https://www.ebay.com/itm/Edelbrock-553-Aluminum-Tri-Power-Manifold-For-Ford-Y-Block-With-Carbs/173467085826?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D20160323102634%26meid%3D57fe9adf214a4fd5a81f224bdb6d0a49%26pid%3D100623%26rk%3D5%26rkt%3D6%26sd%3D183390150347%26itm%3D173467085826&_trksid=p2047675.c100623.m-1 

Nothing is always simple or follows a pattern, right?  


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

I have a 354 on my 239. There’s a picture somewhere on this site. I lost all my pictures when the screen on the IPad was replaced.

  Dennis in Lititz PA

Jack.  Click the link below for a report done by Ted Eaton, one of our Forum moderators, who did some extensive dynometer testing on 3x2 intake manifolds marketed back-in-the-day for use on Ford y-block applications.  Not all makes of aftermarket manifolds perform equally!

http://www.eatonbalancing.com/2013/12/18/y-block-ford-3x2-intake-testing/

Hope this helps.  


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

You know that sounds like a reasonable explanation.

I was told by Joe Craine (a y-block guru) that the 573 is the "good" one.  I actually bought a 573 on ebay for a couple of reasons.  1)  I can work on the other one at my leisure while I still have a running old classic.  2) I simply did not know what I have.

By the way, on all the old Edelbrock y-block manifolds I have seen, the model number appears right below the Edelbrock name on the side as shown in photo.

Jack.  I can understand why you are puzzled about the casting numbers displayed on your Ford y-block intake manifold.  The manifolds I'm used to seeing for your application usually have the casting numbers displayed in the order 573 rather than 357.  Maybe it was a crazy Monday or Friday in the aluminum foundry and somebody affixed the pattern numbers in the wrong order.  Thinking about it another way, perhaps at an early point in Edelbrock production of this manifold offering, the numbers were used in the different sequence. 

See the link below for a current listing of a N.O.S.Edelbrock 573 intake manifold being offered with a set of Stromberg carbs.
https://www.ebay.com/itm/Edelbrock-573-Y-block-ford-tri-power-intake-manifold-with-carbs/123335807360?hash=item1cb7631180:g:H8AAAOSwV01bhGE5

Someone on here may have one like you've got and reply as well.  


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

thats a 57 intake.that is not the model number

I have this Edelbrock tri-power manifold on my '56 292.  It looks like model #357.  However; that model number is for a scruby small block.  Attaching a phoyo.  Any experts out there?