the tranny is essentialy the same, the linkage to you six will be different because a gmc six is different than a chevy six.

the hydro's are rare enough. in a truck they are rarer still and in a chevy they are too rare. so that might answer some questions from blasphemers who imply you should replace it witha four speed.

Lots of literature out there. it comes up on ebay often enough so stick with what you have and dont be afraid