I'll venture to guess there are a lot more 1966 Fairlane/Falcon 289 28 spline wide ratio 4 speeds (HEH BV) out there than 427 Cobra 4 speeds (HEH BY)? It's clear as day to me that is a Y stamped over a V in that photo. Also, what is that hole that appears to be tapped in the left side of the tail housing?