Save yourself the trouble and get a Dex III/VI equivalent. I work at a Valvoline and we preform fluid exchanges (not flushes) on people's trannys all the time, but I will not service GM vehicles with our universal fluid. I've only heard of one person's car having trouble after using it, but I play it safe and just don't.

I honestly did two pan drops with Walmart's Super tech Dex VI fluid with a shift kit and filter a few months ago, and my tranny has been solid ever since.