Ian, I removed the balance tube from the manifold and it has N30 on the bottom. I am very happy with the way the engine looks with all the fresh plating. I sandblasted every part with a very fine powder and had them plated again. If you look closely they show their age (small dents from rust) but the overall picture is very nice. I also replaced all the nuts and bolts with stainless steel items (purchased a set from www.zcarcreations.com) and changed all the bolts of the carburetors with stinless steel allen head bolts. And then I broke my balance tube..... Regards Emil