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# 990730030A.
OWNERS OF SOME VEHICLES EQUIPPED WITH HYDRA-MATIC 3T40, 4T60, 4T60-E OR 4T65-E TRANSAXLES MAY COMMENT ON A GRINDING AND / OR GROWLING NOISE THAT IS NOTICEABLE WHEN STANDING IN PARK ON A HILL OR SLOPE WITH THE ENGINE RUNNING AND THE PARKING BRAKE NOT APPLIED. *TT