markr, I too am in the process of installin' a new Teleflex tach in place of the Merc tach on my float. Mine is just a 90HP Merc but if it is referrin' to the same thing as mine, the reference to poles is in accordance to the number of poles on your alternator. My tach is an alternator driven tach; countin' the number of pulses from the alternator. Check with your shop guy (not the salesmen) and see what number of poles your alternator has. It just maybe that that is what is bein' referred to. Hope this helped. BTW, didn't your new tach have some instructions? That should be explained in there somewhere.