Slip Yoke ? for 1966 Barracuda F/S - 833 trans

I believe the long length & hollowed out bore was for the yoke seal described in my service manual. It has (2) spiral rings holding it in place as shown in the exploded view diagram (item #23). I think without the longer Yoke the seal would be of no value. I don't have enough long term experience with the 4sp to know how necessary it really is. I believe the tail shaft end oil seal would provide sealing which is probably why I have had no leakage in that area. Since I have redone the complete engine and drive train just gaining from FABO experience as I reassemble everything.