Try this.
http://www.antiquechevytrucks.com/Co...ont_suspen.htm
I don't know yet if this is applicalbe to the Task force trucks, but I've seen a few of the AD trucks done this way, track is a little wider though. I've also got a '57 and was going to look at this a little harder, but was leaning towards the Heidt's IFS.
Hope that helps??