I was wondering if they were interchangeable or if there was some special diffrence between them that made the tta's specific to the tta cars such as a special valve body or a special plate on the side?
Nope. Valve body is a teenzie weenzie bit different but you would never know. It has a tad different shift valve spring for the 3.27 gear. As far as interchangeable? By all means "Yes".The only other difference is the TA utilized a constant bleed forward clutch system that the GN didnt have. however, either one works fine. They are kinda interchangeable. Here Read this. http://turbobuick.com/forums/showthread.php?s=&threadid=43172