[patrickt]

Page 32 of the FIA Manual says:

"Stock series 600 transmissions have an input shaft that requires a spacer between the transmission and bellhousing. A transmission with a shortened input shaft is available from various sources and obviates the need for the spacer."

On the 427, it is easier to get everything to "line up" when using the spacer, I don't know if that is different though on the FIA.

EDIT -- Check page 82 of the manual, it has a diagram showing the TKO600 both with and without the spacer. I can't tell what you have to do to make the shifter handle come out in the right place though.