or... you make a reverse design where you put the pivots on the diff on either end and then have two plates coming down off the sub frame with a row of holes which where you can move the position of the center pivot. Have a look at that famous ae86 drifter in australia has, josh?
I myself will make my own center pivot but I will go for the more traditional single pivot on the diff style. I worked out how I can use the original pan-hard pivot on one end and a simple bracket on the body for the other. To find out more look up what the supertaxi holdens and fords do. So might you be able to show a pic of the ford design? also whats the measurement from the center of middle pivot to one of the outer ones in the middle linkage?