Help! Stall Converter fail to work

So your "Stall Converter" fails to convert stalling into motion eh? I assume you are trying to say that following the installation of a new Torque Converter, the car will not move. As others have said, you may have gotten a bum part, and/or you may have spline compatibility issues.

You may have also broken the front pump drive lugs off. It happens, I've done it. If the converter is not seated all the way over the lugs (you use a tape measure and a straightedge to measure this) bolting the transmision to the engine will break these off. Unlike with a manual trans, you should never have to "draw in" an automatic with the bellhousing bolts. In fact, you should have to pull the converter forward about 1/2" to get the flexplate bolts started. I've made this mistake, and it will result in a no-drive, just as you describe (actually it worked just long enough to get me out into traffic). Look at the front pump and you should see the two lugs which engage the notches on the converter drive tube. If not, there's your problem.

Wasn't 68 the spline changeover year?