it should be a matter of swapping the arm out for the new one and tuck the wires into the column
most gm multi-function switches are the same for that era and look like this pic
to remove the arm; push the arm in hard towards the column, twist it and then pull it out of the blinker switch
my truk has an 1986 astro column that i had to swap out the switch to match my aftermarket cruise control
