Does anyone know exactly how the speedo hole is configed within the lower housing? I originally thought it was a curved tube cast within the lower housing. Now I'm not so sure. The merc manual states do not go deeper than 2 7/16" to clean out a plugged hole. Both of my lower units (side water pick up), I can stick a wire in 4 3/4" deep. If you visualize location of the yellow connector, its 4 3/4" back from the lower housings leading edge. The same distance as what I can push i straight wire in. This seems logical. And if I come down vertically from the top where the yellow connector is, I can stick a wire in straight down to where its at the same level as the pick up hole. So basically its just an 'L". But why does Merc say 2 7/16 max depth, when that hole is 4 3/4" deep where it intersects with the vertical hole?