While checking my motor today I noticed that the boots on the plug wire are different color on each end. I also noticed that the inside is different with one being smooth and the other having two rings. On the outside both ends say Delphi but one has three arrows, one of which points straight and the other 2 at 90 degree angles. Which end goes on the plug and which on the coil? Most had the ringed end on the coil. Seems that would be the plug end tp me but not sure. Any help?