I know this may sound like an oxymoron, but I actually like the way the auto works in my '72. I even say this after having done a five speed/3.9 rear conversion on a similiar car. My current car has a 3.9 rear from a Nissan 720 4x4 and this alone was a good improvement in acceleration(especially since I have the '83L28/early E-88 combo). Now for the question(s). What can be done for modifying the stock auto for more perfomance? Are there spec/performance differences between the different years of auto trans? How about the ZX turbo auto trans? Is there anything desirable about it for me? What is the effect of varying the spring pressure on an adjustable vacuum modulator? What is the effect of changing the length of the vacuum modulator pin? I have several in different lengths that I have not yet installed. Hopefully, there are others out there who could benefit from some information on this/these subject(s).