I don't think anyone sells the spacer seperatly. Mopar used to have a shift improver kit and it was in it but I haven't seen it for yrs. I measured the depth once on a 727 and it was a few thousandths over 3" so I cut them to 3" and if the valve body sets down good I let it fly at that. You may have to grind it down a little but 3" is a good starting place. It really doesn't need to be longer. Not one of those things that needs to be precise, just close.