It's hard to say how many manifolds were made but the trick here is to say that only 16 sets are known to have been sold? That could be true.
It depends on who you ask and if you are relying on Kleinpeter that almost disqualifies that number immediately.
Always a salesman and throwing so much at you that you need to choose and pick which you can listen to?
Still, after all of these years very few manifolds have shown up. If the bulk of the manifolds are sitting somewhere, no one seems to know where? Maybe they got junked? 100 castings is the usual minimum casting numbers any of the US foundries will do. That usually is only on "favor" to Ford Engineering requests since they get enough business in total from them to make them interested at all.
I don't think even Willis knew the answer although I'm not sure if anyone ever asked him.
The carb and mounting flanges on the Hall are thicker. The originals are like the original GT40 manifold and they can crack near the last bolt so be careful and hand tighten the bolts gently snug.
Also use silicone on the ends. Not the cork "s" gaskets in the intake kit.
The original castings are a little rough so the ones that I have seen were all painted black. I've only seen a few. It's a great collectors item but no one wants to sell theirs.
The carbs it doesn't really matter. They are all '70s castings and the same as current castings with the extra side tabs. The '60s 48 IDA's cast without those and serial numbered are the "valuable ones". On a race car though "Concourse correct" hardly matters.
Best of luck in "flushing one out" of a collection.
Attached is the response letter that I got from Detomaso. It is from 1979.
The total for the kit was 1,200,000 lire. About $1,560 in US dollars.
Even with a favorable exchange rate in '79, it was not a cheap kit. Linkage was just a Mr.Gasket bell crank and -3 rod ends with 3/8" aluminum hex rod with jamb nuts.
Carbs were WD priced here in the US at $238 each because there you were buying 4. Detomaso's price, about $157 each. That was a good deal,
By comparison, a 2x4 Holley for a 289 Ford was under $500. A 2x4 set up was never available for a 351c other then a tunnel ram.
A Doug Nash split magnesium manifold with two Ford Autolite 1400cfm inlines was about the only alternative.
I've got pics of that here somewhere. The problem with that one was the idle circuits weren't as smooth a transition as the Webers. A steep learning curve is one thing but reinventing the carbs was entirely something else. You were COMPLETELY on your own and might as well have been from another planet?
Understanding how an individual runner manifold works along with it's pulsing reversion helps. There the crash course in Weber 48ida's helps but why do anything logically?
Incidentally, be aware that this manifold will only fit iron 4v heads as far as I know. Most or the aftermarket aluminum heads are at least 5/8" shorter on the bottom and will not cover the bottom of the port of the manifold. There are so many choices now I can't say all but many of the ones I've seen won't.
Hall does (or did) offer two manifolds. One for the iron 4v heads like the Detomaso one. One for the "high port" aluminum heads.
I've had both. I run A3 heads and that manifold is raised 1/4" on top and 5/8" on bottom to match the almost square ports of those heads. They sort of look like the "rectangular" BB Chevy ports?