I picked up an old manifold that is a dead ringer for the Datsun competition manifold. The only problem is that while doing research I came across the Tomei manifoldwhich from the photos looks exactly the same. Did Tomei manufacture the Datsun competion intakes or did they just copy them? 

The stand-off way out on the left side seems to match. This is a unique identifier.

 

You will have to measure port taper and diameters to absolutely make sure they are the same.

Sure is pretty!

Looks like there are at least two Tomei Intakes for 44mm and 50mm carbs:

 

http://www.frsport.com/index.php?target=catalog&mode=searchImproved&cid=1770

 

 

http://www.frsport.com/Tomei-14001R501-Intake-Manifold-Kit-Solex-44mm-Weber-45mm-Carburetor-Nissan-240Z-70-73_p_201637.html

 

http://www.frsport.com/Tomei-14001R502-Intake-Manifold-Kit-Solex-50mm-Weber-48mm-Carburetor-Nissan-240Z-70-73_p_201638.html

I figured that the old one I have is a Datsun competition due to the just the wear and tear visible on the linkage and intake itself. There are actually quite a bit of these types of intakes for sale on yahoo auctions japan. I saw one the other day for about 70 dollars. My guess is worst case scenario about 100 dollars to ship one stateside. Not sure if there might be a resale market for them. I think that last rare intake I sold was a Mikuni shorty which I got close to 400 dollars for with complete linkage. My plan is to pick up a digital gauge and take some measurements. Maybe someone who has one can chime in. 

Measured the intake which came out to 44 on the carb side and 35mm on the engine side. The first photo is of the intake in Japan which matches my intake except for the bar that connects the runners one the one side. I was also able to find a NOS Nissan Comp intake with ad though that one doesn't come with measurements. 

I picked up an old manifold that is a dead ringer for the Datsun competition manifold. The only problem is that while doing research I came across the Tomei manifoldwhich from the photos looks exactly the same. Did Tomei manufacture the Datsun competion intakes or did they just copy them? 

 

I have the manifold pictured on the left for 44PHH Mikuni. The linkage on the Tomei is the better set up.

The one on the left is like mine. Pretty poor design and mostly usless for getting all carbs synced up.

As it is not adjustable. I will be doing modifications to mine to correct that or find a Tomei linkage kit.

Thanks for pointing that out, that really helps to solidify that the one I have is an original Datsun Competition version since it has that non adjustable type linkage on it also. I am going to be getting an aftermarket linkage for it also.