Late update:
My 1987 300D had a stacked (way too early) 3-4 shift... it would essentially skip 3rd gear at part throttle. So, I bought the Superior kit in June 2009, and it sat on my shelf collecting dust for a full 5 years. Yikes.
Anyway, I finally installed the stacked-shift correction spring for the 3-4 shift in early June (2014). The instructions fail to mention that you need to drop the valve body to replace this spring. What a pain! And a royal mess, too. All for one tiny little spring. The good news is, the stacked shift issue is much improved. The issue is still present at light throttle... but at medium throttle, it will now stay in 3rd gear for a reasonable amount of time. I swapped the spring just prior to a fluid change, I wanted to make sure it was working before I poured in ~$100 of fresh Red Line D4. After testing with the old fluid, I did the fluid & filter change, everything has been ok since. I did not replace any other springs, the other shifts were all (relatively) ok, considering the trans has 325kmi and has never been rebuilt.
Tip Of The Day: If you leave the trans pan below the tranny to catch the dripping fluid while R&R'ing the valve body... make sure you drain the pan before attempting to re-install it. Otherwise, you will get a very nice, very red, ATF bath. Don't ask how I know. For the record, I learned this a year or two ago during a different
VB removal... managed to avoid multi-quart ATF puddles this time.
