Sorry, the NHTSA has not posted this TSB document yet.
You can still get the detailed info from Chevrolet for this TSB. Call your local Chevrolet dealer's service department & ask for a copy of TSB# RCL/93C56A.
Affected Component: POWER TRAIN:AUTOMATIC TRANSMISSION
GENERAL MOTORS HAS DETERMINED THAT CERTAIN 1993 M/L AND G VANS MAY EXPERIENCE A CONDITION, AT TEMPERATURES BELOW 32 DEGREES FAHRENHEIT, WHERE THE TRANSMISSION WILL NOT SHIFT OUT OF PARK WITH THE BRAKE PEDAL DEPRESSED. TO PREVENT THIS CONDITION FORM OCCURRING, DEALERS WILL REPLACE THE CRUISE CONTROL VACUUM RELEASE VALVE AND CHECK AND ADJUST THE BTSI SOLENOID CABLE. *TW