They are the same thing as model T glands in function but not in size. I had to machine my own rings. And from there I had to make them again because they were different sizes from each other, and the head holes may be a different size from the manifold. Theyre not difficult but require a lathe and some careful measuring. I made mine a snug fit, tapped in with a rubber mallet. I think i had to hand fit them with a file and a dremel to lightly loosen things up enough for a clean insertion. Absolutely test fit everything before bolting it all down with the rings if they are snug because you dont want to crack the spindly cast iron manifold octopus. If theyre too tight or misaligned checkagain and again, or make a ring looser. I cut the manifold gasket out of high temp gasket sheet from napa as rings on each port, closely fit on the gland rings which held the gaskets in place for assembly. I put copper silicone on both gasket surfaces to be safe and as a check to make sure the manifold actually pressed down fully. No leaks yet, but Im still just test running.