A good screw-in compression tester should have 3 hoses, a short-reach and a long-reach 14MM thread, and an 18MM thread for early Ford OHV V-8's, and a few other oddball engines with big-thread plugs. I think the early International tractors ran an 18MM plug, but the vast majority of engines use 14MM threads. All the stovebolt engines I'm aware of use a short-reach 14MM thread plug.
Jerry

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