Just noticed in plugging one of the vacuum ports of the 1jz intake manifold, it is a approximately 1/8 NPT, but very tapered thread and a bit finer. Matches one of my taps labeled 1/8-28 pipe. Researching further it appears Toyota still used (at least in some locations) the 1/8-28 BSPT. I believe that is what I am trying to plug. My 1/8 NPT plugs would not even get started in the thread, so found a plug in the 1/8 BSPT from Grainger, should be here in a few days. Hope it fits.