worn transmission valve body

my truck has a rather firm 1-2 shift, whether its hot or cold. apparently this is caused by a worn valve body. there is a tsb about it, code 1870. i'm taking it to to the trans shop tomorrow to get it scanned, and see if the code appears. ( i have the exact symptoms the tsb shows) so i was wondering, is this a fairly expensive/time consuming job? about how much money would it cost to the valve body replaced?

1999 chevy s10 4.3 V6, 4L60e auto trans

thanks

http://www.gmtruckhq.com/drivetrain/...1870-1578.html