I would suggest a shift kit or valve body upgrade for ALL transmissions. I put manual valve bodies in all my trans, 904 and 727. The TA RMVB in my 904 would swap right into a 727 if I were to choose to. If the 904 in my Duster fails, I will rebuild it or the other 904 in my garage. How would I be "money ahead" by purchasing a SB 727 along with the proper slip yoke rather than just slightly beefing up the 904 I have ?