On the switch, i can't speak for the '73 and up crowd, but on the '72 and down, you can get a brake light switch for a truck with cruise control. That will give you the terminals on the switch that you can use to disengage the lock up. However, it would be engaged as soon as you let off the brakes too, so it is only 1/2 the solution.
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The hot rod;
a'69 G.M.C. Short/Fleet. 350 W/a heluva cam and nice stance. Trying to clean up the left over damage from the Dope-Smokin-Old-Man. See it at
http://geocities.com/andys_69_gmc/
I've been dubbed the Longhorn
Freak/Fanatic/Expert, I just hope I can live up to it. Check out my Longhorn site at
http://geocities.com/MotorCity/Flats/8752/
Need to pick up the
one ton Longhorn with a 350/350 here soon,
thanks every one! 
If you need a pic posted, e-mail me at
longhornmail@yahoo.com