Hsss,
My name is Jimi, I sell these particular units, if you are going to use the spacer plate you will have to use the original input, the short shaft is used to take the place of the adaptor plate. With the original cast Ford bell you would not need the adaptor plate or the short shaft kit, but it is not SFI approved like the Lakewood bell. You cannot use the adaptor plate and the short shaft together, it will not work, it will space your input to far from the pilot bearing. I have sold hundreds of these units, and several to C.C. members installing them in Cobras, and they either had the short shaft installed or got the adaptor for the back of the bell. Let me know if you have anymore questions, and I will answer them as best as I can.
jimig@standardtransmission.com
Jimi G.