89 Sub w/T400... From the day I bought the truck it has shifted hard. The seller had told me that he when he owned it he had a shift kit installed, so I really didn't think anything of the harder than normal shifting. But recently it started shifting Harder and Harder. I also noticed that my shift points have been moving on up the speedo. It was shifting into 2nd at about 27mph and wouldn't get into 3rd until 56mph, which is way high for normal driving. It was getting old real fast. And recently putting it in gear from Park has made for some HARD HARD HARD shifts. So today I checked my fluid level and it was AOK. I just couldn't figure out what was going on. WELL... It was the little piece of rubber hose that attaches to the Modulator. It was cracked wide open. I went and scavenged a piece of fuel line and slipped it in place... and guess what? It shifts perfectly. I am going to replace my Modulator because there was a little tranny fluid in the vacuum line, but other than that. It works perfectly now. I am just sharing this info and I hope it helps someone out there later on.