what would cause my transmission to shift sometime and not at other time? on 1993 GMC Vandura 3500

my transmission shift sometime rough and other time it will not get out of second gear.

by in Mount Vernon, NY on August 21, 2012
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2 answers
ANSWER by , August 21, 2012
Dii you check for codes in the computer???
ANSWER by , August 23, 2012
Detent cable adjustment.