A buddy of mine has a built 4l80e with a vig 3600 converter. The car has a switch to lock the converter up and lower the rpms. How expensive would it be to build a similar trans? Is it the conveter thats diffrent, or is it something else? I have never heard of something like this b4 i saw it in his car, so im guessing its expensive.

 

You usually don't manually lock it, it should lock on its own when driving around town normally.

The time the switch would be used is say half way down the track in the 1/4 you would lock it so it would pull harder.
Someone correct me on the second part if I'm wrong, but I believe that is correct.

 

Sounds like you friend has a manually controlled transmission and the lock up solenoid is still controlled by a solenoid which is manually controlled by the switch. It is something you can add to any lock up transmission, but I think it is better to adjust the tune to what you want. If you are looking for WOT lock up, you can still add that in the tune.

Chris