[71RestoRod]

I also used the AA output shaft with the 700R4/205 and moved the engine forward. So far it's working great for me.

One advantage to the spacer that I haven't seen mentioned here is that the spacer will give you better clearance between the 205 front yolk / CV and the pan under the 700R4. With the AA shaft you're pretty much stuck with a stock pressed steel pan but I've heard that using the spacer provides enough clearance for a deep pan w/o modifications. Had it been available at the time (or had I known) I would have gone that route instead and moved both the engine forward and the cross member back.