way i look at it its $3000 for a little bolt on that changes a 3spd to a 6spd, OR (for me) the heart-break of cutting my poor old classic up to fit s big ol' tranny with stock Overdrive......i really love my car =D
To use the GV as a 6 spd, you have to time your shifts with both the shifter and the OD switch. It's not automatic. The switch is usually another dimmer switch mounted on the floorboard.
You also must take into consideration the engine rpm at cruise speed being under the stall speed of the converter. If it is, the converter will slip and build heat, decreasing the life of your trans. Done them, too.