I recently installed a new "Z spec" T5 in my 1966 Convertible. The installation was straightforward and I love the new transmission. I am however experiencing a slight annoying leak at the rear seal of the transmission. I used the original four speed driveshaft including the yoke. The driveshaft was shortened 1/2", had new u joints, and was balanced. Was using the old yoke my mistake? I notice in catalogs that T5 conversion kits include a new yoke. Is the O.D. of the yoke shaft slightly larger than the original yoke? Or is it that the old yoke is worn?